Ilkay Gundogan suffered another injury scare after his return to the Manchester City starting line-up was cut short.
Germany midfielder Gundogan tore his right anterior cruciate ligament against Watford last December but came on during a 6-0 win over the same opponents on Saturday.
City boss Pep Guardiola handed the 26-year-old a start in Wednesday's EFL Cup third-round clash at West Brom and Gundogan was instrumental in a superb first-half showing from the visitors.
Leroy Sane opened the scoring in the third minute after Gundogan had a shot saved but the former Borussia Dortmund player had his outing curtailed before the hour.
Gundogan broke up a West Brom attack and embarked upon a driving run into the opposition half, when Claudio Yacob brought him down with a heavy tackle form behind.
Yacob, who later equalised for Albion in the 72nd minute, was booked by referee Mike Jones and, after a lengthy period of treatment, Gundogan limped off the field and down the tunnel accompanied by City's medical staff, with England full-back Kyle Walker sent on in his place.
Gundogan was in the latter stages of his recovery from a dislocated kneecap when he joined City from Dortmund - an injury that forced him to miss Euro 2016, while a back problem kept him out of Germany's triumphant 2014 World Cup campaign.