Manchester City were left to count the cost after Joe Hart limped off in a doubly damaging Champions League defeat at Juventus.
City lost control of Group D as they were beaten 1-0 in freezing Turin while of equal concern was the loss of Hart to a hamstring injury in the latter stages.
Manager Manuel Pellegrini was already without six senior players, including captain Vincent Kompany and playmaker David Silva, at Juventus Stadium, while leading striker Sergio Aguero is still short of match-fitness.
To lose Hart for the weekend clash with Southampton would be another major blow with the England goalkeeper having been in fine form this season.
Hart said after the game the problem was "nothing - just a little bit tight" but he and Pellegrini will have to wait until after assessment back in Manchester to learn the full extent of the injury,
In this moment, it is impossible to know. He has a problem in his hamstring.
Caballero replaced Hart for the final nine minutes but it was another substitute, Raheem Sterling, who captured the attention as he spurned a good late chance to equalise by shooting wide.
City had trailed since Mario Mandzukic volleyed Juventus ahead in the 18th minute. Mandzukic was later denied a second by a fine Hart save and Paulo Dybala hit the post but City also had numerous other chances in an entertaining contest.
Fernandinho blasted over when well placed, Yaya Toure twice went close and Fernando had a header touched onto the post by Gianluigi Buffon. The veteran Juve goalkeeper also denied Aguero just before the break.
Juve's victory not only secured their place in the last 16 but took the Serie A champions ahead of City and into prime position to advance as group winners.
City have fared badly - twice being drawn against Barcelona - after finishing as group runners-up in the past but Pellegrini looked on the positive side.
"I think the group is not finished. Of course it was a chance tonight at least to draw, but we will continue to depend on what we do in the last game.