Carlos Alcaraz made it back-to-back Madrid Open titles with a hard-fought three-set win over Germany's Jan-Lennard Struff in Sunday's final.

Taking on a first-ever Masters finalist, home favourite Alcaraz survived a second-set scare to triumph 6-4 3-6 6-3 against lucky loser Struff, taking two hours and 25 minutes to defend his crown.

Early nerves got the better of Struff, who double-faulted twice in the first game to gift Alcaraz an early break, but the German gave the teenager a good run for his money early doors and broke back to love in the fourth.

However, another pair of double faults from Struff allowed Alcaraz to break again in the seventh, and despite falling 0-40 down when serving for the set, the 19-year-old saved all three of those break points to come through a tricky opener.

Struff had shown plenty of verve in the first set, though, and the 33-year-old stunned Alcaraz in the early knockings of the second, winning the first three games and remarkably saving five break points to hold for a 4-1 lead.

Alcaraz could not respond in what remained of the second set, but the Spaniard won four of the first five games in the deciding set, racking up nine winners and retaining his crown with a final love hold.

The Spaniard now has four ATP Tour titles from five finals this year, winning 10 top-tier trophies in total as he sets his sights on a maiden French Open honour later this month.

Prior to Alcaraz's victory, Aryna Sabalenka sunk Iga Swiatek to get her hands on the women's crown on Saturday.