Dick Advocaat has warned Jack Rodwell that his fitness must improve if he wants to become a regular at Sunderland.

Having burst onto the scene as a teenager at Everton, the 24-year-old’s career stalled following a move to Manchester City in 2012, making just 16 appearances in total for the Citizens.

The lack of game time prompted a £10million switch to the Stadium of Light last summer and he has shown signs of improvement for the Black Cats, although he is yet to truly establish himself.

Part of Rodwell’s problems over the years has been down to his fitness, with him having to battle a persistent hamstring problem for much of his time at the Etihad.

However, whereas he was a fringe player at City, the three-cap England international has the ability to be one of the leaders on the pitch for Sunderland as boss Advocaat looks to guide them away from another relegation scrap.

The Dutchman believes the midfielder is still to show his best form on Wearside and, although he admits it has not all been the player’s fault, he has warned the 24-year-old he must get stronger.

“I’ve had a lot of words with Jack because he is such a talented player,” Advocaat said. “He has not shown that for me, and he knows that.

“It has not all been down to him, because it has also been because of his physical state. It has to be better.”

With a full pre-season under his belt, Rodwell will be hoping to earn a starting role for Sunderland’s opening game of the season at Leicester, a match they are 4.00 to win, with the Foxes 1.95 and the draw 3.25.

An early away win would certainly help their survival chances, with Sunderland currently the 2.75 fourth favourites to be relegated.