23:50 CET - Carlos Alcaraz is also through after beating Tommy Paul in straight sets, while Stefanos Tsitsipas fell to Karen Khachanov.
21:21 CET - Elena Rybakina is FLYING in Miami, beating Martha Trevisan 6-3 6-0.
19:45 CET - And now Fritz is through in relatively straightforward fashion, beating Rune 6-3 6-4.
18:35 CET - In the first match of the day, Sinner has made light work of Rublev, soaring past the Russian 6-2 6-4. The Italian was in simply scintillating form.
16:24 CET - As mentioned, some of the encounters today are mouthwatering prospects. In around 35 minutes, Sinner vs Rublev begins, with Fritz vs Rune starting an hour later. It's nearly time.
10:45 CET - There are some great contests coming up today on the men's side that should be some real heavy-hitting encounters. Jannik Sinner takes on Andrey Rublev, Taylor Fritz faces Holger Rune, Stefanos Tsitsipas goes head to head with Karen Khachanov while Tommy Paul will aim to upset reigning champion Carlos Alcaraz.
Have a look at the men's and women's schedule for the day at Flashscore.
8:15 CET - The contests in Miami are beginning to get really spicy, with the round of 16 on the men's side and quarter-finals on the women's kicking off today.
Overnight, Aryna Sabalenka continued her stunning season with a convincing win over Barbora Krejcikova, while Frances Tiafoe was sent home by Lorenzo Sonego.
See the highlights of Sabalenka's win below, and click HERE if you want to read about all of yesterday's results in more detail, including another win for Elena Rybakina, and a shock exit for Hubert Hurkacz.