Liverpool have won the first domestic trophy in England this season, by beating Chelsea 1-0 in the Carabao Cup on Sunday.
The 90 minutes ended without any goals, although two were chalked off by VAR in both halves.
Both Raheem Sterling and Virgil van Dijk saw their efforts ruled out after checks.
However, with penalties looming, Van Dijk rose highest to head past Petrovic.
The win kept Liverpool’s hopes of an unlikely quadruple alive and saw them lift the Carabao Cup for a record-extending 10th time.
Chelsea’s run to the final had emerged as a silver lining for coach Mauricio Pochettino in what has been a bleak first season in charge of the west London side.
But with Sunday’s defeat, the former Tottenham boss still has yet to win a trophy in England.