The 20-year-old Canadian continues his impressive run, beating Giron in straight sets to reach the last four. Elsewhere, Rublev also moves into the Halle semifinals.
The 23-year-old Russian ousts Jordan Thompson in straight sets and will next play Philipp Kohlschreiber.
The sixth seed needed two tie-breakers to get the better of the Russian qualifier and enter the third round in Paris.
Novak Djokovic began his French Open 2021 in dominant fashion, registering a straight sets 6-2, 6-4, 6-2 win over Tennys Sandgren.
Both Isner and Garin needed three sets to enter the quarterfinals of the Madrid Open.
King of Clay, Rafael Nadal, suffered a shock quarterfinal exit against Andrey Rublev at the Monte Carlo Masters last week.
Stefanos Tsitsipas was in the form of his life last week as he did not drop a set en route to winning the Monte Carlo Masters
The 22-year-old Greek player, Stefanos Tsitsipas, clinched the Monte Carlo Masters without dropping a set in the entire week
Andrey Rublev beats Casper Ruud in straight sets to reach the Monte Carlo Masters final, he will face Stefanos Tsitsipas
Spanish star Rafael Nadal suffered a rare defeat in the quarterfinals of the Monte Carlo Masters against Andrey Rublev