Serena Williams has withdrawn from next week's Italian Open in Rome, it has been confirmed by the tournament.
It is the second successive event the former world number one has pulled out of having also decided not to play in Madrid this week.
Williams made her comeback in March, six months after giving birth to baby Olympia, but focused on training following tournaments in Indian Wells and Miami as she attempted to return to top shape.
A statement on the tournament's Twitter feed read: "We are so sad to announce that @serenawilliams, a 4-time Champion in Rome, has withdrawn from #ibi18. Obviously we can't wait to see her again on Foro Italico's red clay, perhaps in 2019?"
There must now be some doubt over whether Williams will play at the French Open later this month. Were she to make her grand slam comeback at Roland Garros, it would be without having played a match on clay since 2016.