Substitute Campo led the Bolton celebrations

The Premier League side took a one-goal lead into the away leg and reduced favourites Atletico to half-chances.

"We were forced to defend by a very good outfit," Megson told BBC Sport.

"We had the one-goal lead but we sat far too deep. But in the second half we did much better, I've never once had to criticise them for a lack of effort."

Interview: Bolton boss Gary Megson

606: DEBATE Give your thoughts on Bolton's win

Megson added: "We're doing a lot of things well at the moment, but all that doesn't mean a massive amount until you've achieved something."

Bolton skipper Kevin Nolan said his side deserved their place in the next round.

"It's fantastic what we've achieved - we've gone one step further in the competition than we did last season," he said.

"The way our team played over the two games, I think we deserved it.

the lads just got on with the job Defender Nicky Hunt

"The Premier League is our main focus, but we want to go as far as we can in the Uefa Cup."

Defender Nicky Hunt paid tribute to his side's work ethic on the night.

"The work-rate was the best I've seen from the team, " he said.

"It was always going to be difficult playing in front of a hostile crowd but the lads just got on with the job. We kept them to shots outside the box."