Top seed Andrey Rublev crashed out of the St Petersburg Open after a straight-sets defeat by Dutch qualifier Botic van de Zandschulp in the quarter-finals.

A recent US Open quarter-finalist, world number 69 Van de Zandschlup claimed the first top-10 win of his career on Friday.

The 26-year-old also advanced to the semi-finals of an ATP event for the first time.

There, he will face 2011 champion Marin Cilic, who was a 6-4 3-6 6-3 winner over third seed Roberto Bautista Agut.

Denis Shapovalov was another big-name casualty in Russia, the second seed going down 4-6 3-6 against world number 53 Jan-Lennard Struff.

Although, there were better fortunes for fifth seed Taylor Fritz. The Indian Wells semi-finalist is yet to drop a set this week after prevailing 6-4 6-2 against John Millman.

Elsewhere, Matteo Berrettini was the victim of another upset at the Erste Bank Open in Vienna.

The Wimbledon champion went down 1-6 7-6 (7-2) 6-7 (5-7) following a two-hour 40-minute battle with Carlos Alcaraz.

Reaching his first ATP 500 semi-final, the Spanish teenager claimed another big scalp having defeated Stefanos Tsitsipas at Flushing Meadows last month.

However, second seed Alexander Zverev remained on course for a fifth title of the season, as he claimed his 300th tour-level win.

The Australian Open finalist beat Felix Auger-Aliassime 6-4 3-6 6-3, avenging his fourth-round defeat by the Canadian at Wimbledon in July.