Swansea manager Michael Laudrup admitted his side had paid the price for a lack of concentration in their Europa League draw with Kuban Krasnodar.
Michu's 68th-minute goal saw the hosts leading going into stoppage time when Swans keeper Gerhard Tremmel brought down Ibrahima Balde, and former Liverpool forward Djibril Cisse equalised from the penalty spot.
Swansea remain top of Group A with seven points, one ahead of Valencia, who thrashed St Gallen 5-1.
"Overall, it was a fair result," said Laudrup. "When you are 1-0 in injury time, they get a counter, we should have kept the ball.
"They hit the counter, with two or three half chances. We had a lot of possession but did not create too much.
"When you are 1-0 up into injury time, you can call it frustrating. We have to move, we have to play until the last second. Now we will have to do our work away from home."
Swansea defender Neil Taylor added: "We are massively disappointed to be honest. We were not at our best, but in the second half we ground them down.
"They gave it everything today. There is always a chance at 1-0. If we play to our top level then there are not many teams who can cope with us. That at the end is a sucker punch.
"You have to be strong and hold out. We switched off for 10 seconds, and that happened. It is not easy to say it is positive now. It should have been another win for us."