Capital One Cup.
Michu and Danny Graham both scored for the Swans after two huge mistakes by Branislav Ivanovic outside his own box.
The West London club dominated in parts but failed to turn their control of the game into goals. However, Demba Ba replaced Fernando Torres late on to score a goal, which was swiftly disallowed for offside.
Benitez was disappointed by the decision to rule out Ba’s goal, saying, “The goal was a goal, he was level.”
The Blues now go to the Liberty Stadium with the burden of clawing back two goals away from home.
Despite the glaring mistakes on the field, Benitez was reluctant to place any blame upon his players.
“The team is doing well. You can lose a game and then analyse it, but if you play this game 10 times maybe you will win nine of them,” Benitez told Sky Sports.
“I think the team were doing really well, had a lot of chances and could have scored two or three in the first half but we made two mistakes and paid for them.
“I can see any player making mistakes and it’s not an issue. It’s about trying to do things afterwards, and Ivanovic tried to do his best. We carried on and tried to do the right things.”