Stoke - Andre Villas-Boas endured an frustrating start to English football management on Sunday as Chelsea was held to a 0-0 draw by Stoke in their Premier League opener.Stoke keeper Asmir Begovic tipped over a dipping volley from John Obi Mikel and a curling shot from Nicolas Anelka in the second half.Chelsea had several penalty appeals turned down, including when Salomon Kalou fell following Glenn Whelan's tackle and Frank Lampard went down under a challenge from Marc Wilson."It is not easy to play against Stoke and this is only the first game of many we have to play and we have to start thinking about the next one," Chelsea striker Fernando Torres said. "We are happy with the performance but not the result."We are disappointed with the result. We had some chances to score and two very clear penalty situations, but we had enough chances so it is no excuse."Villas-Boas, a former Chelsea scout under Jose Mourinho, was hired to replace Carlo Ancelotti after the Italian's second season in charge ended without a trophy.But despite recruiting the manager who won four titles with FC Porto last season, little appears to have changed at Chelsea over the summer.As well as Stoke's physicality, last season's runners-up had to cope with incessant pressure.A throw-in from Rory Delap and a couple of corners from Jermaine Pennant caused some early trouble in the Chelsea penalty area and set-pieces continued to cause problems throughout.Late in the first half, defender Jose Bosingwa and goalkeeper Petr Cech managed to keep out Matt Etherington's in-swinging free-kick under the crossbar at the near post after John Terry had stopped Kenwyne Jones.But for all their endeavours, the hosts' attack could not match the quality of Chelsea's.Torres, who started ahead of Didier Drogba and Nicolas Anelka, showed glimpses of the form he enjoyed at Liverpool before his move in January.But the Spain striker failed to find the target, with just one goal now to his name in 19 Chelsea appearances."I was happy with my performance today - a striker always likes to score but it is not always possible," he said. "I am only 27 and I haven't forgotten how to play and score, last season was a season to forget for me but it is in the past."