Andy Murray says he does not know the extent of his abdominal injury but hopes the setback does not derail his grass-court season.
Murray, due to play at Queen's this week before Wimbledon in a fortnight, received medical treatment twice and was in visible discomfort when serving.
"Hopefully it's all right," he said.
"Obviously I've played a lot of matches. This is the most matches I've played in two weeks since probably 2016. That's a really long time.
"It's probably normal that I would feel some stuff in my body but I don't really know the severity of it.