Top seed Denis Shapovalov failed to reach the semi-finals of the Stuttgart Open as his busy Friday ended with defeat to Marin Cilic.

Shapovalov had earlier completed a rain-delayed match with Feliciano Lopez, winning in three sets.

However, the Canadian was beaten in two tight sets by former US Open champion Cilic, who prevailed 7-5 7-6 (7-3).

"I felt I was applying a little more pressure during that first set and I capitalised on the couple of break points, which was definitely big, just to give me a bit of extra momentum," Cilic said.

"I also had the two match points at the end of the second set, didn't convert them, but played a really good tie-break. You always have to expect tough battles against top guys like Denis and it was like that today."

Cilic will face Jurij Rodionov after the Austrian came from behind to stun fourth seed Alex de Minaur, a player ranked 120 places above him, 3-6 6-3 7-6 (7-4).

Shapovalov's Canadian compatriot Felix Auger Aliassime remains in the draw, though, going through to the last four with a 7-6 (7-5) 7-6 (10-8) win over Ugo Humbert in which he hit 17 aces.

Auger Aliassime, the lone seed left in the tournament, is hoping to repeat his run to the final in 2019. Standing in his way will be the sizeable figure of Sam Querrey, who ended wild card Dominic Stephan Stricker's superb tournament.

Teenager Stricker had match point at 5-4 in the second set but Querrey fought back to progress 6-7 (4-7) 7-6 (7-4) 6-3. Querrey won all 14 of his first-serve points in the final set.