A 2-0 defeat to Swiss side FC Basel saw the Scottish champions, who lead 3-1 from the first leg, tumble out on the away goals rule and sees Celtic go into the Uefa Cup draw on Friday.

Manager Martin O'Neill broke with his normal 3-5-2 formation in favour of a back four, but the system proved flawed as an uncomfortable Celtic were torn apart in the opening stages and found themselves two down after 22 minutes.

O'Neill admitted his side's first-half display dashed their Champions League dream after his tactics backfired in the St Jakob Stadium.

"I am obviously very disappointed, but we didn't play well enough in he first-half," conceded O'Neill.

"In the second-half we threw everything at them, but it wasn't to be, but full credit to Christian's (Gross) side.

"They played very well especially in the first-half.

"We knew that we had an advantage going into the game and we wanted to keep that advantage for the first 25 minutes of the game.

"That was the reason I played the four in defence, but they scored twice in that time.

"We abandoned it at half-time because we needed to score a goal.

"I felt even with the team in the first-half that were capable of scoring, but we just didn't defend well enough at set-pieces."

O'Neill reverted to a back three after the break, but despite some good opportunities, the visitors were not able to take them.

He continued: "We changed the system and even though we had the majority of play, we just weren't able to take chances."

The Celtic boss refused to make excuses even though referee Andres Frisk failed to award them a second-half penalty after Alexandre Quennoz handled the ball in the box when in a prone position.

O'Neill muttered: "On the penalty I don't know what happened."

FC Basel manager Gross was revelling in the moment and described his side's display as "perfect."

The former Tottenham boss enthused: "It was a pleasant night for us. We started the second leg in the best possible way.

"I am glad for the the players, the city and the crowd. This is a great achievement."