F1 World Champion, Mercedes' British driver Lewis Hamilton, offers a press conference in Sao Paulo, Brazil, on November 8, 2017 ahead of Sunday's Formula One Brazilian Grand Prix. / AFP PHOTO / Nelson ALMEIDA (Photo credit should read NELSON ALMEIDA/AFP/Getty Images)

There are two 23-year-olds that will be keeping Lewis Hamilton awake at night for the foreseeable future. In fact, one could go even further by saying that in all likelihood, these two 23-year-olds will be a thorn in Hamilton's side until he eventually retires. Indeed, Max Verstappen and George Russell aren't going anywhere anytime soon. So is this a fight that Hamilton can win, or is he too long in the tooth to defend his crown?

Let's start with the Dutch Grand Prix and Verstappen's runaway victory in front of his home fans. The flying Dutchman was able to win back-to-back races following the conclusion of the summer break and by doing so, also able to steal a march on Hamilton and top the 2021 drivers' standings. Worryingly for Hamilton, it did seem like a matter of time before this happened given that the Englishman was only really able to dislodge Verstappen after the 23-year-old ended up crashing in consecutive Grand Prix races.

That was something that he did twice, but curiously, both times involved Mercedes' drivers. You can understand how aggrieved Red Bull and in particular Verstappen would have been heading into the summer recess. However, two faultless drives without any tangles with Hamilton or Valtteri Bottas have restored the 23-year-old's lead since then. It may only be a slender one - a mere three points - but Verstappen's odds of 8/13 to win the 2021 championship in the latest F1 betting tips tells a story in itself. Basically, if he can steer clear of the wheels of the Mercedes drivers, the expert opinion is that he may end up cantering to the title.

That is certainly a thought that will keep Hamilton tossing and turning, but any respite from a disturbed night won't be forthcoming after Mercedes announced that 23-year-old driver George Russell would be replacing Bottas, showing that Toto Wolff has decided that the Englishman is the future of the team. Russell will have to prove himself, but anyone watching F1 over the last season will expect him to excel at Mercedes and even challenge for the 2022 title.

With all of this in mind, it's probably fair to say that Hamilton's world is changing a lot quicker than perhaps he thought it would. Indeed, he will be involved in a direct battle with the future of F1. So, can he prevail? 

'Only for so long' has to be the answer when you consider that at 36, the Stevenage-born driver is very much in the twilight of his career. Having been in the F1 game a long time, Lewis Hamilton would have seen countless examples of older drivers being put to the sword by the next generation but soon, he will have to fend off two blades. 

The writing seems to officially be on the wall for one of the all-time greats of the sport, but that's not to say we won't see one last courageous stand and an incredible eighth championship win.