LONDON (AP) — More than just a blip in form, Jose Mourinho’s Chelsea Premier League title defense is in trouble after only four games. There’s a long way to go but a 2-1 home loss to Crystal Palace on Saturday left the champions trailing irresistible leader Manchester City by eight points and added the gloom around Stamford Bridge. This stadium once seemed to be impenetrable for Chelsea’s Premier League opponents. Not this season. Although this was only Mourinho’s second home league loss in 100 games, it followed a 2-2 draw with Swansea on the opening day in west London. “It’s difficult to not only overcome the quality of the team but the manager here,” Palace manager Alan Pardew said. “This team today just had a belief they were going to win.” FOLLOW THE DAILY NEWS SPORTS ON FACEBOOK. “LIKE” US HERE. Not since 1982 had the south London team won a game at its rival north west of the River Thames. “We deserved more, I don’t want to say we deserved to win because it’s not true,” Mourinho said. “Four points in four points is a very bad start.” The second-half collapse reinforced the need for defensive reinforcements, with Chelsea’s…