Carlos Alcaraz celebrated "being almost at the door" of becoming the top ranked tennis player in the world again after defending his Madrid Open title on Sunday.

The Spaniard earned his 10th career title with a hard-fought 6-4, 3-6, 6-3 win over Jan-Lennard Struff and can reclaim the world number one ranking from Novak Djokovic simply by playing a single match at the Rome Masters next week, before the French Open.

Currently ranked second, Alcaraz spent 20 weeks in the top spot after his US Open triumph in September, becoming the youngest player to reach world number one.

Djokovic's Australian Open triumph saw him depose Alcaraz but the 20-year-old confirmed he would play next week in the Italian capital.

"These are very nice achievements, winning my fourth Masters 1000, defending my title here and being almost at the door of recovering the number one spot," Alcaraz told a news conference.

"These are very big things I'm doing, and I'm very proud of the work and of these accomplishments. I am ambitious and we'll try and go for Rome."

Alcaraz continued his Roland Garros build-up by adding the Madrid trophy to victories in Barcelona, Buenos Aires and Indian Wells this year, although he was below his best against lucky loser Struff, the world number 65.

The triumph and his impending return to the top of the rankings reiterated his bright future at the game's summit.

Alcaraz said his only worry for his future in tennis is injury, rather than any mental aspects.

"You have to try to take care of yourself as much as possible," said Alcaraz.

"The mental issue, of getting tired of winning, travelling or playing tennis, doesn't worry me because I know it's not going to happen.

"What may worry me in the future is the issue of injuries, which is what we are going to try to take care of together with my team."

- Title defence -
Alcaraz was given a tricky time by his German opponent but eventually became the youngest player since Rafael Nadal in 2006 to defend an ATP Masters 1000 title.

Despite being 13 years Alcaraz's senior, Struff showed nerves in the first game and conceded a break in only his second tour-level final.

Struff soon found his range and broke to love for 2-2 as he showed Alcaraz he would be no pushover, despite the strong home support and their disparity in ranking, and then won a third consecutive game.

However Alcaraz broke again for a 4-3 lead and survived a triple break point to win the first set.

Struff's power game created plenty of problems of Alcaraz -- hitting 14 winners in the first set to the Spaniard's seven.

"I knew bombs would come my way, Jan is very aggressive," said Alcaraz.

Struff roared into a 3-0 lead in the second set and produced a remarkable hold in the 15-minute fifth game for 4-1, saving five break points as Alcaraz's hitting deserted him.