Cahill will not be leaving in January, says Megson

Bolton manager warns off any prospective purchasers for highly rated centre-half

Cahill has suffered a blood clot in his arm (AP)

Gary Megson, the Bolton manager, is determined to hang on to highly-rated defender Gary Cahill, admitting it would be madness to cash in on a player who has not yet reached his peak.

The 23-year-old has forced his way onto the fringe of Fabio Capello's England squad after a number of impressive performances for Wanderers since his £5m move from Aston Villa in January 2008.

Capello was in the crowd to watch Bolton's 2-1 victory at Birmingham on Saturday and Cahill has already been linked with Tottenham, Milan and Juventus. The centre-back has twice been called into the national squad to cover for injuries but could earn a place on merit when the Italian coach makes his selection for the forthcoming World Cup qualifiers against Ukraine and Belarus.

Megson moved quickly this summer in getting Cahill to sign a new three-year contract, removing a reported £8m release clause, and has no intention of letting his defensive linchpin leave.

"This club got itself into a nightmare scenario over Gary," he said. "There was a set fee that he could have gone for. We did brilliantly in the summer to get rid of that and we're in a position now where we don't have to sell him. Football-wise it would be madness to sell him in January."

Megson knows the damage losing key players in the winter transfer window can do after selling Nicolas Anelka to Chelsea for £15m in 2008 – although he used some of that cash to buy Cahill three weeks later. "Selling real assets in January is a nightmare," Megson added. "We've been there before with Nicolas Anelka, didn't win in 10 games and escaped relegation only by the skin of our teeth in the last five games."

The Burnley centre-half Clarke Carlisle has called for him and his fellow defensive colleagues to get their act together. The Clarets lost 5-0 at Tottenham on Saturday and have now conceded 14 goals in four matches away from home without managing to score, contributing to a goal difference of -10 despite being 11th in the Premier League.

Fortunately Burnley's record at Turf Moor is 100 per cent , with three victories and just one goal conceded but Carlisle is conscious, ahead of the visit of Birmingham on Saturday, that there is work to be done after consecutive defeats.

"With Tyrone Mears and Andre Bikey being relatively new to the back four it's very important we do sit down as a defence this week and lay out what we expect of each other in a certain situation," Carlisle said.

"There will be differences of opinion, which is excellent, but [all that matters is] when it comes to a Saturday we're doing the same thing. I would rather we all did the wrong thing – whether we're all 10 yards off or all 10 yards up – as long as we did it together.

"Sometimes there are no answers because there are some spectacularly fantastic players in this league. You find the crispness and quality of passing is such that you can't get anywhere near."

The visit of Birmingham signals the start of a period of matches during which Burnley will look to pick up points after facing the likes of Chelsea, Liverpool and Manchester United in their first seven games.

"It's been a tough start, a tough sequence of games," Carlisle said. "When you're not picking up results they become harder games because it's a higher pressure situation. We're coming to a run of games now where I think people will be expecting us to be picking our points up. It's all about maintaining focus and discipline."

Bikey has been included in Cameroon's squad for a World Cup qualifier against Togo on 10 October and a friendly against Portugal four days later.