The delay was in excess of 15 minutes, so Tsitsipas and Sinner have been given three minutes to warm up ahead of a resumption of play.
Tsitsipas leads 6-3, 2-1.
But the commentators believe the new conditions – under the roof – will favour Sinner.
â€œWeâ€™re not going to go through that awkward part of the day with the shadow moving across the court. Weâ€™re now under lights here,â€ Sam Groth said.
â€œWe saw how well he [Sinner] played against Alex De Minaur once the sun moved away. I thought he was much better in sets 1, 2 and 3 once the sun cleared and he was out of that heat. You spoke about where heâ€™s grown up, what heâ€™s trained in and where heâ€™s lived all his life. The ball is no going to jump around.
â€œThe way Stefanos was bullying Sinner around the court, thatâ€™s going to be way more difficult for Tsitsipas to do. The air is going to cool down, the air-conditioning will kick in and the ball wonâ€™t fly through the air so much.â€