Fritz beat Australian Alex de Minaur in the first match, and when Sinner took on Daniil Medvedev a few hours later, both could celebrate their semi-final place in Turin.
Sinner won the pool, while Fritz came second. On Friday, Ruud, Carlos Alcaraz, Alexander Zverev and Andrej Rublev will play for the semi-final places from the second pool. Everyone can advance, but Rublev is the only one who cannot win the group.
Zverev has the lead in the pool before the final round, while Ruud is number two. Ruud will play against Rublev, while Alcaraz and Zverev meet.
Ruud opened the tournament by beating an ailing Alcaraz. On Wednesday, there was a loss against Zverev.
Read also: Brilliant serving not enough – Ruud lost to Alexander Zverev
Read also: Verdensener Sinner dominates in Turin – beat Fritz with Pirlo in the stands