They are fine matchups and we'll have a mix of players that were considered next-gen until not long ago with Rune and Sinner belonging to the current next-gen. The first one will begin not before 13:30 local time and it will be the 7th time they played against each other. Fritz leads the matchup 4-2 so far but they never played on clay.
Rublev has been really good at this event for many years but Fritz can certainly do some damage if he puts enough pressure on Rublev. He has won the past three meetings between them. The second one will see Sinner take on Rune and it's going to be a blockbuster. The starting time will be no sooner than 15:30 local time.
Expect the Italian crowd to show up in support of Sinner but Rune loves playing in those conditions and he'll happily play the villain if he needs to. Their only previous match happened last year in Sofia when Sinner retired down 2-5 in the final set. Both are fine clay players and it should be great.
Semi-finals Day Schedule:
13:30 Taylor Fritz v Andrey Rublev
15:30 Jannik Sinner v Holger Rune