Basel, Switzerland, 23 October 2019 | AP

Alexei Popyrin’s big serve was nullified by Fabio Fognini as the Italian accounted for the Australian young gun in the opening round of the Swiss Indoors.

Popyrin served seven aces but had his serve broken four times in the 6-2 6-4 defeat, finishing the match with 30 unforced errors to Fognini’s 15.

Popyrin, who beat Joao Sousa and Soon Woo Kwon to qualify for the main draw, had won five of his past six matches coming into his clash with Fognini.

Yet the Italian’s ultimate 77-minute victory boosted the fifth seed’s hopes of qualifying for a maiden appearance at the season-ending ATP Finals.

“Tennis has started to change again with these young guys who are amazing on their first and second serves,” Fognini said. “But I’m happy because I’m 32 and still winning against some of them.”

In other first-round action on Tuesday in Basel, second-seeded Alexander Zverev was eliminated 7-6(7) 6-4 by Taylor Fritz, who advanced to set up a showdown with Australian No.1 Alex de Minaur on Wednesday.

De Minaur and Fritz will play at approximately 5.30am Thursday AEDT.

Zverev led 4-0 in the first-set tiebreaker and held a set point before Fritz took his chance to clinch it with an ace – one of 14 for the match.

The 31st-ranked American got the only service break of the match in the third game of the second set and converted his first match point with a two-handed backhand winner.

“I played really solid, so it feels good to get that (win) instead of him getting me for the third time in a row,” Fritz said.

The defeat harms Zverev’s hopes of defending his ATP Finals title next month. The German is seventh in the season-long standings to advance to the eight-man event in London.