Wigan manager Roberto Martinez was happy to keep the bulk of his squad together during the summer transfer window.[LNB]Antonio Valencia and Lee Cattermole were the only high-profile exits from the DW Stadium, and Martinez is convinced he has a squad strong enough to compete in the Premier League.[LNB]He told the club's official website: "You always need to look to help the squad you have.[LNB]"I'm not the sort of person to just bring in players for the sake of it, Wigan Athletic doesn't work like that.[LNB]"In that respect I'm delighted with the squad I have here and now we need to work hard and achieve our potential as soon as we can.[LNB]"One of the most important things for us was to keep hold of our key players, those who have been attracting interest from elsewhere."