Swansea manager Michael Laudrup insisted his side still had "a mountain to climb" to reach the Capital One Cup final despite their 2-0 win at Chelsea.
Michu and Danny Graham pounced on mistakes from Branislav Ivanovic to give the Swans a commanding advantage to take into the return leg of the semi-final in a fortnight.
But Laudrup warned against writing off the quality of Chelsea, who dominated throughout at Stamford Bridge but were unable to take their chances.
"We've had some historic results already this season but to win at the European champions is very special," Laudrup said. "To be honest I'm delighted with the result.
"But there is still a mountain to climb. They have so much quality and we will
have to play exactly the same; with the same intensity. They could still score three of four goals against us.
"But I am most happy about going into the second leg at home with a possibility to play a final at Wembley."