Barcelona's qualification for the Champions League knockout phase with two games to spare has been overshadowed by a serious thigh injury to midfielder Andres Iniesta.

The Spain international will likely be out for six weeks after straining his right thigh muscle in the second half of Barca's 1-1 draw against Group C rivals Basel at the Nou Camp, a result that was enough to send them through to the last 16.

"Iniesta's injury is very bad news for us," coach Pep Guardiola said.

"It's never good to have an injured player," he added. "He's an important player for us but injuries are a part of football."

The Catalans had won their previous 11 matches in all competitions ahead of Tuesday's tie, and took over at the top of the Primera Liga on Saturday with a seventh consecutive win.

A six-week absence would mean Iniesta missing league ties against close rivals Real Madrid, Villarreal, Valencia and Sevilla, as well as Barca's last two Champions League group matches against Sporting Lisbon and Shakhtar Donetsk.

Barca were leading 1-0 with less than 10 minutes left on Tuesday thanks to a goal from substitute Lionel Messi before Eren Derdiyok came off the bench to score the equaliser.

Guardiola said he was unhappy with the result but pleased to be through to February's knockout round.

"I don't like the fact we drew, but maybe the result will do us some good," he said.

"It is only November and we have qualified for the next round with two games to spare, so that's a positive."

Captain Carles Puyol said Iniesta's injury had dampened the mood in the dressing room.

"Andres is very important for us and we hope he will recover soon," he said.