Leach, who has been Ben Stokes' main spinner throughout his tenure and came into this match as the leader of a three-pronged spin attack, sustained the injury trying to save a boundary on day one before aggravating the knee in Friday's morning session. It limited the left-arm spinner to just 16 of the 87 overs in the day, bowling at most four overs in a spell and at times leaving the field for treatment.

"He banged his knee last night, the first dive down at fine leg," Jeetan Patel, England's spin-bowling coach, said. "Then he banged it again today and it's giving him a little gyp, to be honest. You noticed in the outfield he was a little sluggish trying to get to balls, but he stuck at it and I thought he actually bowled really, really well considering.

"It must be pretty serious, or serious for him anyway, because the reality is he wouldn't shirk that responsibility. It is sore enough. You watch him in the outfield and I don't think it's a graze. For him to come back and keep bowling the overs he did... I believe he'll be back in the fourth innings.

"That's what Jack does for this team, he'll always put in. But it's an bit of a shame from where he's come [recovering from a stress fracture of the back last summer] to dive on one at fine leg and all of a sudden you're hobbling around. He'll be back. He's one of the strongest guys in the team. We've had to share the load and the I thought the guys did really well."

Patel remained bullish about England's chances despite the match situation but ceded success, both in the match and the series as a whole, is reliant on improvements to Leach's knee overnight.

"He's got another night to rest it. He's a tough bloke and he'll be raring to go," Patel said. "He's never going to shirk the responsibility of the job he has, but it's about being smart as well. We've got four Tests to go and another innings at the back end of this game. We need a key man like Jack."