In October this year, just two months into the new season, Wayne Rooney will celebrate his 30th birthday.
It is strange to even write that sentence, for it does not feel like 13 years since Rooney made his debut as a teenage scamp in an Everton shirt.
At just 16, he scored that goal against Arsenal and launched himself into the Premier League as a burst of perpetual energy to terrify the best defences.
Since then, a debate has raged as to whether Rooney has fulfilled his potential, but five Premier League titles, one Champions League and nearly 250 career goals should always settle it in his favour.
This season, Rooney could also pass Sir Bobby Charlton to become both Manchester United and England’s all-time leading goalscorer.
But on the verge of making history, could this also be Rooney’s final season as the main man at Old Trafford?
It can be dangerous to write him off, for he has already seen off both Cristiano Ronaldo and Robin van Persie during his time at United.
But Rooney is about to enter his 30s and has already played a lot of football.
He has never had a naturally athletic physique, like Ronaldo or Ryan Giggs, and always had to work harder just to stay fit.
His manager of nine years, Sir Alex Ferguson highlighted Rooney's battles for fitness in his 2013 autobiography. As reported by ESPN FC, Ferguson wrote in My Autobiography, "He has great qualities about him but they could be swallowed up by a lack of fitness."
During the late 1990s, I can recall having a conversation with a Manchester United physio about a player and being told he wouldn’t play deep in to his 30s because of his build. He was proved correct.
Rooney has a similar build to this player; he has a naturally stocky frame, and it will become a growing struggle to remain as lean and lithe as he needs to be.
On United's pre-season tour of the United States, Louis van Gaal has been rightly keen to hail Rooney’s importance to his side as his only established and proven striker, as he said in an interview with Sky Sports.
During a period of change at Old Trafford, Van Gaal has wisely recognised Rooney as a symbol of continuity, a player who can inspire and galvanise all the new arrivals.
But Van Gaal can’t afford to be sentimental, his treatment of Van Persie at 31 proved that, and the United manager may well see the end is also in sight for Rooney as early as next summer.
Above all else, Van Gaal cherishes pace in his forwards. It is why he has banished Van Persie and Radamel Falcao and brought in Memphis Depay this summer.
On the verge of turning 30, pace will increasingly become one quality Rooney cannot offer, for he is inevitably getting slower, not faster.
It was during last season, as relayed by BBC Sport, that the United manager declared, “We don’t have a striker who scores 20 goals.”
Can Rooney, at the top of Van Gaal’s preferred 4-3-3 formation, become that striker this season?
In 11 seasons at Old Trafford, Rooney has only broken the 20-goal barrier in the Premier League twice, in 2009-10 and 2011-12.
In the last three seasons, Rooney has managed 12, 17 and 12 league goals.
He remains a fine player, still worthy of the United shirt, but history will judge that the peak of his career came during that 2009-10 season.
At the age of 24, Rooney, finally freed from sacrificing himself for Ronaldo, scored 34 goals in all competitions for United.
Six years on, he is still capable of great moments but is a different player and not quite as dynamic.
A striker at a major club needs competition, and at the moment, only the inexperienced James Wilson and the clearly unwanted Javier Hernandez provide that to Rooney.
It is why Van Gaal is still searching Europe for a new striker (per the Mirror), a younger model with more pace and energy who could eventually replace Rooney.
If Rooney is supplanted up front, it was proven last season he cannot simply step back into the United midfield.
Last season’s experiment when Van Gaal used him there was not a success.
It was decisively proven Rooney’s game is not designed for the intricacies of midfield, with greater patience and shorter and quicker passing required.
There are also no remaining vacancies in midfield after the summer arrivals of Morgan Schneiderlin and Bastian Schweinsteiger, so if Rooney is to prolong his career at Old Trafford, it will have to be up front.
And there he could still enjoy a good season for United, full of important performances and goals, and possibly moments to savour if he manages to overtake Charlton’s records.
But this season, surrounded by younger and sprightlier talents, Rooney could, for the first time, suddenly look like the past and not the future for United.