Long-serving England captain Farrell will become ineligible for international selection under Rugby Football Union rules when he joins French club Racing 92 on a two-year contract in the summer.

After sitting out the Guinness Six Nations to prioritise his mental health, the 32-year-old is set to return to competitive action on Saturday in the Gallagher Premiership clash with London rivals Harlequins.

Saracens director of rugby McCall believes Farrell is capable of remaining at the top level for the foreseeable future, including eventually adding to the 112 caps he was won for his country.

“There are very few players who can and I think he is one of them,” said McCall.

“But you have got to have the drive to do that, you’ve got to have the competitive spirit to do that – I think he has that.

“He can keep going for as long as that drive and competitive spirit is there.”

Fly-half Farrell has spent his entire career with Saracens and is poised to make his 250th appearance for the club in this weekend’s derby against Quins at Tottenham Hotspur Stadium.

“Regardless of what happens over the next 10 weeks, his legacy is firmly established here,” said McCall, who joined Sarries in 2009 when Farrell was still a teenager.

“He’s done everything and achieved everything here.

“And to go and explore the opportunity that he is in France and experience something different with his family, I think is a great thing to do at this stage of his career.

“I can’t imagine Owen Farrell not being in rugby for the rest of his life, to be honest.

“Given the rugby IQ that he has, the motivational ability that he has, the brilliant communicator that he is, the good person that he is, you could see him stepping into coaching very readily and we hope in time that might be here.”

Farrell opted to step out of the limelight after last year’s Rugby World Cup in France following intense scrutiny.

“The break was important for him,” said McCall. “He’s had a personally very difficult time.

“Maybe it’s him being brave enough to talk about it, which is not easy to do for most people, certainly not somebody like Owen.

“I think at least it’s maybe changed the dial a small bit.

“When people talk about England now, it’s never as bad as people are saying and it’s never as good as some people are saying. It’s somewhere in the middle but no-one ever reports it that way.

“I think Owen’s bravery in telling people how he felt was a good thing.

“We almost forbade him from coming [into training] because he needed some respite and needed to go and do some things with his family, some things that were not rugby related. He is now free to throw himself into the rest of the season.”

McCall revealed Saracens have identified a replacement for Farrell and expects an official announcement in the coming weeks.

“It has been a fascinating project trying to find the right person,” he said.

“We wanted to look for someone that we believed had the potential and the personality to be part of this team for a while. We think we have found the right person.”