The Bristol prop has not played since suffering a groin injury during England’s Autumn Nations Series finale against South Africa six weeks ago.
But Bristol rugby director Pat Lam has delivered an encouraging fitness bulletin, with Sinckler on course to be involved in this weekend’s Gallagher Premiership appointment with London Irish.
England kick off their Six Nations campaign against Scotland on February 4, which will be Borthwick’s first game in charge since succeeding Eddie Jones.
Sinckler linked up with England during a get-together this week, and Lam said: “He (Sinckler) should be available this weekend.
“He hasn’t played since the autumn internationals, and rugby players don’t like being out for a long time. They don’t like watching rugby.”
Bristol and England scrum-half Harry Randall, meanwhile, is also on the comeback trail following a hamstring injury.
“This guy (Randall) has been out for 12 or 13 weeks, so you can imagine what he is like,” Lam added.
“He is raring to go and is not far away.
“He was on the training field yesterday and just has to tick off a few markers on the medical and strength and conditioning side, and he will be good to go next week.”
Lam said that he has already caught up with Borthwick, who is also planning on a visit to Bristol’s training ground.
“He is moving around the clubs, which is good,” Lam said. “That is what you want from an England coach.
“Any time there is a new coach coming into clubs or internationals, it is a clean slate for all players.”