It was the American statesman Benjamin Franklin who said that ‘nothing is certain except death and taxes’.

That was back in 1789: had he been at The Den on Saturday, he might have been tempted to add Watford winning on the opening day of the season and Mileta Rajovic scoring from close range.

The Hornets have taken three points in the first game in each of the last five seasons, while Rajovic scored his 12th goal for the club to secure the 3-2 win – a header from four yards, bringing his average scoring distance for the club to 4.8 yards.

It was a topsy-turvy, harem scarem, nerve-jangler of an afternoon in south-east London with an ultimately happy ending and an overall feeling that Watford looked better than many people expected.

It was the sort of game that, had it been described to fans before kick-off, they would have delightedly accepted – but because none of us knew the script in advance the portion of the action between 2-0 and 3-2 was uncomfortable viewing.

What it did show was character, and an obvious desire to play for head coach Tom Cleverley coupled with a belief in what he wants the team to do.

The latter was true in both the good and the bad elements of the performance, as both goals conceded came as a result of sloppy errors which were made as players were attempting to play their way out of defence.

Cleverley said after the game that is how he asks his team to play, and they will get better at it over time. If you are going to learn the errors of those ways, then doing so in a game you win is probably the best time.

It was a character-laden 90 minutes from those in yellow, which started before a ball had even been kicked.

The extremely poignant tributes to late Lions keeper Matija Sarkic pre kick-off quite understandably sent a wave of emotion around the stadium – admirably contributed to by the away fans who did Watford proud – which then morphed into a decibel or two more noise in a venue where intimidating atmospheres are always on the menu.

The Hornets dealt well with the opening 15 minutes which is when a Millwall cavalry charge often makes visiting sides crumble.

A combination of Watford’s high line and extremely effective pressing meant the home side were never able to pummel the visitors back into the own third.

It was amazing how quickly, being sat in a home stand, you could hear and feel the mood and attitude of Millwall’s fans change. Even before Watford went ahead there was concern from the Lions fans that they weren’t getting the ball forward quickly and directly enough.

That was largely due to Watford steadfastly refusing to allow that, which takes some cojones at most grounds but particularly at The Den.

The opening goal, while sweetly-struck directly from a corner by Edo Kayembe, had more to do with an obvious error by Millwall keeper Lukas Jensen who seemed so preoccupied with what was happening around him that he completely forgot to watch the flight of the ball and it sailed over him and inside the back post.

Amid all the celebrations it was noticeable that Ryan Porteous went to great lengths to pacify some of the actions of his teammates who were keen to ‘give a bit’ to the home fans.

Not a wise thing to do at The Den, and certainly not with an hour or more left to play. The Scottish defender may have his own rash moments, but that was a mature and wise action in a instance when it would have been easy to allow joy to overtake rationality.

The midfield pairing of Moussa Sissoko and Tom Dele-Bashiru exerted more and more control as the game wore on, and their willingness to take the ball off teammates in cramped and tricky positions meant Watford were constantly able to pick their way out of tight spots.

As referred to earlier, that approach also led to errors which contributed to the two Millwall goals, but as Cleverley pointed out after the game, simply hoofing the ball into Row Z might provide temporary relief but it inevitably leads to another surge from the opposition and consequently they push you further and further back.

The Hornets possibly used up their day’s luck in one attack when Ryan Andrews appeared to sweep away Duncan Watmore’s legs inside the box. Referee Mr Busby had a great view but probably didn’t have time to blow for a penalty when the ball broke to George Honeyman.

He then sent a shot against the left-hand upright, but got a second bite at the cherry as the ball hit the grounded Bachmann on its way back into play and sat up perfectly for Honeyman again.

This time he found the centre of the goal, but waiting there was Francisco Sierralta who dropped to his knees to block – the ball then rebounded straight to Bachmann and somehow Watford had survived very strong penalty appeals, a strike of the post and a goalline clearance in less than five seconds.

The start of the second half saw the home side do what many expected they would accomplish from the start, and that was push Watford back and largely keep them penned in.

At the back, Mattie Pollock really caught the eye. The big defender won pretty much everything that came near him, and what he didn’t win he made sure the opposition didn’t get easily.

Considering he was playing on the left, Pollock looked assured and confident, and in the form he showed on Saturday it’s hard to imagine a Watford back three without him.

Clearly there were still some crumbs of good fortune left after that Honeyman escapade because George Saville sent a header against the upright, and the visitors badly needed to break the trend of the opening exchanges of the second period.

All game long, the best and most effective outlet for Watford was to get the ball to the feet of Giorgi Chakvetadze and let him run directly at the Millwall defence.

They never seemed quite sure how to deal with that threat – dive in and risk being jinked past or conceding a foul; back off and the Georgian will happily rampage as far as he is able.

In the 55th minute Millwall did a bit of both, as Chakvetadze broke from just outside his own box and was finally brought down almost 30 yards from the Lions goal.

When he stood alone over the free-kick it was one of those ‘surely he’s not going to…’ moments, and that thought hadn’t had time to fully enter the mind when Chakvetadze stepped forward and curled a magnificent effort over the wall and inside the post.

It was a truly stunning free-kick, bringing back recent memories of the likes of Abdi and Toszer, and even Barnes and Callaghan for those of us older fans.

It capped a superb all-round performance from Chakvetadze who already looks pivotal to the Watford system. There’s no doubt other teams will be wise to what he can do but, as Millwall showed, even with the benefit of scouting and video analysis it’s not always as simple as telling your players not to let him do it.

I remember Graham Taylor saying to me once, when he was talking about the Liverpool team of the early 80s that boasted the likes of Kenny Dalglish and Ian Rush among their immense attacking threat – “I knew what they would do, I just didn’t know how to stop it.”

Suddenly there was breathing room and a 2-0 lead that looked like it would be enough to make sure of the points.

However, one thing you can be certain of at The Den is that the home side don’t fold, and Neil Harris made changes from the bench to galvanise his team.

Even so, it still came as a surprise when Millwall pulled one back but, when they did, there was a dramatic switch in the mood of the home fans and the earlier discontent was replaced by a surge of optimism.

If Duncan Watmore’s first goal was poor from a Watford perspective, his second was very bad as there were more assists from players in yellow than blue before Watmore, to his credit, finished off with a sweetly-struck shot into the corner.

In that moment, there was genuine fear that what looked like a comfortable opening-day win could be flipped into being on the wrong end of a sun-kissed fightback victory for the hosts.

Thankfully, there was barely any time for the Lions to build on their equaliser before that man Rajovic popped up with the winner.

The Dane is a player that splits the fanbase: some just don’t see how he fits into the way Watford play, others think he just needs time to learn.

What neither camp can ignore is his ability to be in the right place at the right time, and whatever you make of him any player that scores a goal every 160-odd minutes adds a threat.

On Saturday, Rajovic showed great anticipation and awareness, and often that is something that is a sixth sense which great strikers say comes naturally.

When Tom Dele-Bashiru got the ball on his right foot on the edge of the box in the last minute of normal time and shaped to curl a shot with his right foot, there were three Millwall defenders and Rajovic in line with the penalty spot.

As the shot deflected up into the air off the leg of Saville, the three defenders stayed where they were but Rajovic had already started to move towards the goal, timing that drift forward perfectly so that he stayed onside.

Keeper Jensen edged a couple of yards towards the ball but Rajovic’s movement ensured he got there first and a deftly-directed flick from the striker steered the ball down inside the far post.

It’s often easy to overlook the intuition and precision of a goal scored from close range, but Rajovic keeps doing it and deserves credit for it.

There is something to work with – that’s been the phrase that has come back at me when I’ve spoken to various coaching staff that have worked with Rajovic since he signed last summer.

He may not be the first choice in the No.9 role, given Cleverley is set to bring in another striker. But every team needs impact players and Rajovic’s record suggests he can be just that.

The nine minutes of stoppage time were as tense as you’d expect, the large amount caused by a bloody clash of heads which meant a large white bandage and a clean shirt for Pollock, and eventually led to the replacement of Ryan Leonard, who looked pretty shaky but was allowed to play on for several minutes.

There was just one scare as the clock ticked down when Watmore was presented with a great chance to complete his hat-trick from a central position but saw his low shot gratefully smothered by Bachmann.

The final whistle brought joyous celebrations between the away end and the Watford party, exacerbated by the manner of the late victory.

And why not? It was the first time Watford had won or even scored at The Den since 2015, and Millwall manager Harris suffered his first home defeat since returning to the club last season.

There were areas that need to be worked on – defending of set pieces still needs plenty of attention for instance – but this was a very creditable victory where Watford showed a clear plan, how they can pose a threat and character to deal with setbacks.

As last season illustrated, winning the opening game is no litmus test for the season as a whole, but this was a victory to be enjoyed and a performance to offer much encouragement.