​Saido Berahino's stuttering ​Stoke City career has suffered another setback, with manager Paul Lambert admitting that the out-of-favour striker is not fit enough to play for the first team.

Berahino has played 13 times in the ​Premier League this season, mostly from the bench, but has not scored a single goal for the Potters since joining the club in January 2017. 

His last senior goal was for former club ​West Bromwich Albion against ​Crystal Palace in February 2016: over two years ago. The Burundi-born forward was once seen as a future England star, but is now a peripheral figure in Lambert's relegation-threatened side.

And the Scottish boss stressed that Berahino must work on his fitness if he is to ever become a Stoke regular again.

"He's not up to my level of fitness," said Lambert, as quoted by ​Sky Sports. "He's a fit lad, but there's got to be more to it, that he's got to work on.

"I have told him that, so he knows the situation and what I'm explaining. I think he's been really good with me working away at it, but it has to come from him as well.

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"We have given him a wee programme to stick to as well. We're in a situation where we need everyone to perform when they're called upon.

"I think he's [Berahino] an absolutely fantastic, incredible finisher, but you need a bit more at times," added Lambert. "I don't think he's up to the levels [of fitness] he should be."

Stoke won 2-0 against ​Huddersfield in Lambert's first game in charge, but have failed to win in their subsequent four matches, leaving them 19th in the Premier League. They face a crunch trip to ​Southampton on Saturday afternoon.