Frank Lampard believes Chelsea can claim victory against Barcelona in the Champions League semi-final after reaching the last four by defeating Benfica 3-1 on aggregate.The Blues took a 1-0 lead into the quarter-final second leg against the Portuguese side and survived a late scare when Javi Garcia's equaliser put his side within a goal of progressing.But after Raul Meireles smashed home in injury time to secure a 2-1 win at Stamford Bridge on the night, Lampard admitted his mind has already turned to avenging their controversial semi-final defeat to Barcelona in 2009."Everyone's got unfinished business with them," the 33-year-old told Sky Sports."You have to respect they're the greatest team in the world; they have been and still are at the present time."That game is still in our minds, but this is a completely different year so we need to try and beat them."Lampard's first-half penalty had given Chelsea a comfortable advantage against Benfica but they failed to take a number of other opportunities to kill the game off and the England international admitted they had been made to work hard."It was a tough game," he said. "Even though 1-0 away was a great result you know it leaves you in a bit of a conundrum really on how to approach the game."Ahead of Napoli we knew it was all out, today we started a little bit in-between really and gave them a bit of an idea that they could come and win the game."[We're] relieved to get through, they're a good team we have to give them respect but we're pleased to be in the semis."The meeting with Barcelona will be the first time Chelsea have faced Pep Guardiola's side since losing to them at the same stage in 2009. But despite the Spanish side's impressive displays in this season's competition, Lampard is adamant that the west Londoners can get their revenge."Obviously they're going to be favourites because of the way they're playing," he said."We have a lot of belief in ourselves here, we know we'll have to perform at out absolute best to get a result against them and we believe we can do that."