Carlos Alcaraz survived a major scare in the opening match of his Madrid Open title defence as he came from behind to beat Emil Ruusuvuori.

The defending champion, who defeated Alexander Zverev in last year's final, was twice broken in the opening set by Ruusuvuori but responded well to prevail 2-6 6-4 6-2.

Alcaraz hit 36 winners to his opponent's 23 to reach the last 32, where Grigor Dimitrov awaits after defeating Gregoire Barrere 7-6 (8-6) 7-6 (7-2). 

"It was really tough. I would say I was about to lose," Alcaraz said in his on-court interview. "It was really tough. Emil played unbelievably, but I am really happy to get through that."

There was a shock result elsewhere as third seed Casper Ruud lost 6-3 6-4 to Matteo Arnaldi, who had never previously claimed victory over a top-10 opponent.

Arnaldi previously eliminated Benoit Paire and will now take on Jaume Munar – the Spaniard advancing after Tallon Griekspoor retired when a set behind in their second-round tie.

Monte Carlo Masters winner Andrey Rublev continued his good form on the clay courts with a 7-5 6-4 win against Stan Wawrinka.