West Bromwich Albion manager Tony Pulis has backed under-fire goalkeeper Ben Foster ahead of his return to Aston Villa four days on from a costly error in the local derby.

Villa won Tuesday's league meeting with Albion in dramatic fashion after Foster gave away a last minute penalty when he needlessly fouled Matthew Lowton, with the spot kick converted by Christian Benteke.

England international Foster took to Twitter afterwards to apologise for his performance.

But Pulis has refused to rule out giving Foster the chance to earn an immediate reprieve in the FA Cup quarter-final clash at Villa Park on Saturday.

West Brom's reserve goalkeeper Boaz Myhill had been Pulis's first pick for their cup ties, however they have been nursing him back to fitness after he suffered a finger injury against Birmingham in the fourth round.

Myhill found himself among the substitutes in the previous round against West Ham, with Foster selected and Pulis admits he now has a tough decision to make.

"I'll tell the goalkeepers who is playing before I tell anyone," he said.

"How many clean sheets has Ben Foster kept this year? Is it nine? He's been absolutely fantastic.

"Obviously Boaz Myhill had an injured finger so we've had to take that into account.

"We've been talking about referees. They make mistakes. Goalkeepers get highlighted like referees. It can cost you games.

"They had a day off Wednesday so they could dust themselves down and we'll start again."

Victor Anichebe (groin) is again ruled out, while there are doubts over Callum McManaman and Saido Berahino (both foot) and Brown Ideye (knee).

"This is a massive game and we will try and put our strongest team out but we also know there is other stuff further down the line as well," Pulis added.

The midweek win over West Brom was new boss Tim Sherwood's first since taking charge and ended a run of seven straight league defeats for Villa.

"It was a good feeling to get the first win," Sherwood said. "The manner we did, late on in the game, was an extra boost for everyone.

"We sent the fans away happy on Tuesday night. I'm sure on Saturday evening the fans will be up for it again.

"I know we needed a bit of luck at the death but we dominated the football match and we could have gone in at half time three or four nil up.

"It didn't work out that way so we had to show character and dig in. We did that and there was quality there too.

"We'll improve also, so if West Brom improve we will too."

Meanwhile, former Aston Villa skipper Stiliyan Petrov has rejoined the club as part of Sherwood's backroom staff.

The Bulgarian made 218 playing appearances for them between 2006-2012, before being diagnosed with acute leukaemia.

The 35-year-old, now in remission, has come back in a coaching capacity and will work with the first team after being involved behind the scenes on Tuesday.

"I would never bring him in to be a mascot. He's got a very technical and gifted mind, I want him in here as quick as possible," said Sherwood.

"Stan will always have a place at this football club while I'm manager."

Petrov briefly performed the role of assistant of the youth development squad in 2013, yet three months later he resigned from the post citing the need to "build myself up some more" and spend more time with his family.