Tim Sherwood explains his advice to Aston Villa star Jack Grealish

Jack Grealish produced a superb performance as Aston Villa defeated rivals Birmingham City 1-0.

Aston Villa manager Tim Sherwood has told the club's official website that he is Jack Grealish's 'biggest fan' - but admits he has had to tell the midfielder to work harder.

Villa enjoyed a euphoric Tuesday evening, as they beat their fierce local rivals Birmingham City 1-0 at Villa Park in the Capital One Cup.

Jordan Amavi's left wing cross was powered into the net by the head of Rudy Gestede, handing Villa bragging rights - as well as a place in the next round of the competition.

After a dour first half, Sherwood made two changes, bringing on Jordan Ayew and Jack Grealish for Joleon Lescott and Gabriel Agbonlahor - and both substitutes impressed in the second half as Villa took control of the game and looked dangerous going forward.

It was Grealish who impressed the most, and Sherwood reacted to the 20-year-old performance after the game, telling the club's official website that whilst he thought Grealish made a difference, it was largely because of the space afforded to Villa by Birmingham.

"I thought it was easy for him in the second period because the space was there," said Sherwood. "I am not taking anything away from his quality. I am his biggest fan. But it was because there was so much space. It caught them by surprise."

Sherwood also admitted that he has had to speak to Grealish in training recently in a bid to get the mercurial playmaker to work a little harder when he isn't in possession, and backed his star playmaker to become a 'top player' with the right application.

"I had a word with him in the week about trying to put some work-rate in out of possession. I am not asking him to be a tiger in the midfield area but I want him to get back into a shape and that might help him when we win the ball back. It might be easier for people to find him. He's willing to learn - and he has the potential to be a top player," he added.

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