Mercedes have admitted Lewis Hamilton and Fernando Alonso's previous falling out will play a major role in the decision over whether the Spaniard will be recruited for the 2018 Formula One season. With Valtteri Bottas having only agreed a one-year deal with the reigning constructors' champions there could be a vacant seat to fill for the new campaign, with Alonso among the contenders.

Alonso was approached in the off-season following the retirement of world champion Nico Rosberg, but Mercedes eventually lured Bottas from Williams to fill the void. The Fin has impressed in his first five races, winning the Russian Grand Prix having started on pole in Behrain.

Trending: Conor McGregor and Floyd Mayweather fight draws closer

But Bottas' future beyond the end of the season is uncertain and could yet see Mercedes make another change to their line-up. Alonso is out of contract at McLaren at the end of the year and is growing increasingly frustrated having failed to finish four times already this term.

Should Hamilton and Alonso indeed be reunited it would see the drivers paired together for the first since the 2007 season which saw the pair regularly come to blows at McLaren during the Briton's first year in the sport. Alonso would eventually go on to re-join Renault and Mercedes co-owner Toto Wolff admits the episode might play a role in the decision over whether to enlist the 35-year-old.

Don't miss: Tottenham susceptible to losing key stars

View photos Fernando Alonso and Lewis Hamilton More

"Lewis also plays a role, of course, we need two drivers working together for the team, two drivers that are equal in speed to pressure each other and pressure the entire team to improve," he told Marca. "You have to look at everything before you reach a decision.

Most popular: 'Physically, mentally, it's tough' says Nadal on Murray form

"I think the best drivers always accept the challenge and Fernando would clearly be a challenge, but it is much more than Lewis feeling at ease with Fernando, it is the whole dynamic of the team that plays its part and you have to look at the personalities and characters and how they'd fit in.

View photos Lewis Hamilton and Fernando Alonso More

"I think Fernando is a different person today than he was before. The realistic situation is that there are probably other drivers who are would hold priority over Fernando, for the moment. Valtteri and Lewis are the priority, and we look at our juniors, [Esteban] Ocon and the others. He's part of the group, but nothing more."

Wolff however has no concerns over Alonso's ability to match Mercedes' expectations, despite having not won a race since 2013 and claimed just 62 world championship points in the last four seasons. "I am a fan of Fernando [Alonso]'s driving, even if he's not the best then he's one of the best on track," he admitted.

"The pace is there and his motivation is the same... I do not think being 35 is a problem. He's towards the end of his career, but that doesn't mean that he doesn't have three or four years left to win races or championships.

"But right now we have a setup in our team that works and the relationship between the drivers is good and if I could choose Fernando the individual, it would be much easier than choosing the Fernando who has all of this historical background. That said, it's something which we would have to evaluate.

View photos Toto Wolff More