The right-back sustained a ruptured Achilles in an innocuous-looking incident during Wednesday's 1-0 FA Cup fourth-round replay victory over Wigan and will undergo an operation on Friday. Ricketts, who has been a key member of Bolton's back four this season, is expected to be out of action for six months, meaning he faces a battle to be fit for the start of the next campaign. The DW Stadium clash was the second match in a row that Coyle witnessed one of his defenders leaving the pitch on a stretcher after Zat Knight damaged knee ligaments in last weekend's 2-0 Premier League victory over Everton. The Scot said: "Unfortunately Sam's ruptured his Achilles and he'll be operated on today but the likelihood is he'll be missing for about six months, which is an incredible blow first and foremost to Sam, because he's been outstanding for us. "Our immediate thoughts are with him for a speedy recovery and we'll just have to get on with it. It was totally innocuous and it's a real shame because he's a terrific lad as well as a fantastic footballer. "You could see in the dressing room he obviously knew it was a bad one. But he's very strong mentally so, although he'll certainly be disappointed to miss the rest of the season with the lads, I've got no doubts that come the summer he'll come back as big and strong as ever." Wigan's pitch was relaid following Wednesday's cup tie but Coyle denied the state of the playing surface could have been a factor in Ricketts' injury. He said: "There's no blame to the pitch. Roberto [Martinez, Wigan boss] will tell you it's not a great pitch, certainly not conducive to the way Wigan want to play, but there's absolutely no blame apportioned to the pitch with regards to the injury." The Bolton boss also confirmed Knight is likely to be out for six weeks after further assessment of his knee problem. Coyle added: "He's making progress but we still expect Zat to be missing for six weeks, which is not ideal but that's the nature of football with the speed the game's played at at this level. It's a crying shame for both lads because they've been in terrific form." The absence of Wales international Ricketts gives Coyle a real problem for Sunday's FA Cup fifth-round trip to Fulham as both Gretar Steinsson and Jlloyd Samuel, who would be natural replacements at right-back, are also injured. Against Wigan, Paul Robinson switched sides enabling Marcos Alonso to come on at left-back, and that could well be the option the Trotters boss uses again. He said: "As a football club we'll just have to adjust and make the most of what we've got. "We don't have another right-back sitting there waiting to play but we'll look to put out a team that's capable of winning games at the level we play, and that's a great challenge for us all." Coping with Knight's absence is not so much of an issue following the January arrival of David Wheater, and the former Middlesbrough man already looks to have formed a good partnership with Gary Cahill. Coyle added: "Good players enjoy playing with good players and in Zat Knight, Gary Cahill and David Wheater I think we have three fantastic centre-backs. And that will provide real competition for that area of the park when they're all fit."
