A spirited fightback from Nick Kyrgios saw the Australian beat second seed Stefanos Tsitsipas in the Halle Open on Wednesday.

Kyrgios suffered a disappointing semi-final defeat to Andy Murray in Stuttgart last week, but looked greatly improved against Tsitsipas as he recovered from a set down to win 5-7 6-2 6-4.

It was the second serve of both men where Kyrgios shone, winning 76 per cent (28 of 37) of points on his second serve, and 58 per cent (23 of 40) on his opponent's.

"Stef is one of the best players in the world at the moment and he's going to have some amazing results and I'm sure many, many grand slams," Kyrgios said following his win.

"I don't know if I can say the same for me, but I'm happy to still be able to produce this level with the tournaments I play. It is a testament to how hard I do work when I'm not playing."

He will face Pablo Carreno Busta in the quarter-finals after the Spanish sixth seed beat Sebastian Korda 6-4 0-6 6-3.

Elsewhere, Hubert Hurkacz will face Felix Auger-Aliassime in the last eight after defeating Ugo Humbert 7-6 (7-5) 6-3, while the Canadian also won in straight sets against Mackenzie McDonald 7-6 (9-7) 6-1.

The one remaining first round match saw number one seed Daniil Medvedev beat David Goffin 6-3 6-2 to set up a second round clash with Ilya Ivashka.

At the Queen's Club Championships, sixth seed Denis Shapovalov was eliminated by Tommy Paul 6-4 2-6 6-4, with the American now scheduled to face Stanislas Wawrinka in the second round.

It means that six of the eight seeds in west London were knocked out in the first round, with Matteo Berrettini and Marin Cilic the only remaining seeds. The latter sealed his place in the quarter-finals on Wednesday with a 7-6 (8-6) 7-5 win over Alexander Bublik.

Cilic will play Finland's Emil Ruusuvuori in the last eight after he beat home favourite Jack Draper 6-2 7-6 (7-2).

The best contest of the day came between Alejandro Davidovich Fokina and Alex de Minaur, with the former coming from behind to win 4-6 6-4 7-5 to set up a quarter-final with Botic van de Zandschulp, who beat Grigor Dimitrov 7-6 (7-5) 6-3.