Thiago Monteiro spent a good portion of his childhood being driven around by his older brother Faber for hours and hours, from one tournament to another across Brazil, trying to make it as a young tennis player.

He was adopted as a newborn baby and his mother Fatima raised him and his siblings as a single parent, while also fighting breast cancer and dealing with financial difficulties.

On Saturday on Arantxa Sanchez Stadium, at one of the biggest tournaments in the world, the Brazilian world No.118 delivered a huge upset as he handed sixth-seeded Stefanos Tsitsipas a 6-4, 6-4 defeat to reach the third round of a Masters 1000 event for the first time in his career.

Monteiro felt it was a special reward for all the effort his family put in to support him throughout his career.

The left-handed qualifier wasn’t enjoying the best stretch of results on the Challenger Tour in the run-up to the Mutua Madrid Open, which made the win over Tsitsipas all the more sweeter.

“I just try to enjoy the most the tour, because we are very privileged guys to travel the world, to play a big sport and to have this opportunity every week,” said an elated Monteiro, whose exploits at the Caja Magica have taken him back to the brink of the top 100.

“I just try to push my best to give back the efforts that my mom and my brothers put on me to be in this position now. I’m just really happy that I can play in the big tournaments.

“I knew that they were watching me, so I try to push a little bit even more when I know that my family, my friends, everybody is behind me.

“I’m just happy, happy for me, and also happy for them that they can share this moment with me.”

Tsitsipas came into the match looking to build on what has been an impressive 10-1 start to his clay-court campaign, which included a third title triumph at the Masters 1000 in Monte Carlo and a runner-up showing in Barcelona the following week.

The Greek world No.7 arrived in Madrid having reached at least the quarter-finals in nine of the 10 clay Masters 1000 events since the start of the 2021 season.

Monteiro was feeling confident though on the back of three wins at the Caja Magica this week, through qualifying and main draw, and it was evident when he broke Tsitsipas in the third game of the match. The Brazilian lefty maintained his advantage to scoop the opening set in 38 minutes and jumped to a 2-0 lead in the second.

Serving to stay in the contest at 3-5, Tsitsipas saved a pair of match points to hold serve and keep his hopes alive.

Stepping to the line to serve for the victory, Monteiro had to save a break point as Tsitsipas upped the pressure with some relentless defending.

The 29-year-old had missed just three first serves up until that final game, landing a stunning 93 per cent of his first serves in. Things got a tad wobbly as he tried to close out the win but Monteiro sealed the deal on his fourth match point, as a Tsitsipas backhand sailed long.

“He was very aggressive, very persistent. His first-serve percentage was pretty high,” said Tsitsipas, who was a finalist in Madrid in 2019.

“I just wish I was able to return the way I did in the last game. I felt out of rhythm the entire match on my returns. I felt very disbalanced and just, my body was going all over the place.”

Indeed Monteiro put together arguably the best serving performance of his career (he finished the match with an 89 per cent first-serve success rate) to pull off arguably the biggest victory of his career.

“What I’m taking away from this is I saw a few improvements that I managed to make throughout the match. They came quite late during the match,” added Tsitsipas.

“But I think I try and understand from these improvements that I made and reinforce them next time I step out on the court and I’m faced with the same situation again, playing a player who is hungry to beat me, playing a player who is literally grinding, has played a few Challengers in the last few months, and these are the type of opponents that for sure you should be more alert being faced against.

“I really have to continue with humility that I have been showing the last few months and focus on the process that comes with our sport.”

This was the fourth top-10 win of Monteiro’s career and it earned him a showdown with Czech No.30 seed Jiri Lehecka.

At 29 years of age, he is pleased to be hitting new milestones on the tour, and he’ll try to take it further as he seeks a maiden Masters 1000 fourth-round appearance.

“Actually it’s never too late, never too late indeed. I see guys like (Jan-Lennard) Struff that is 32, 33, won his first ATP, last week (in Munich). (Adrian) Mannarino, 35, he had his best season of his tennis career, like, last year,” reflected Monteiro.

“Tennis is like this, one week can change the whole year, the whole plans that you have. You just need to keep working hard and to keep trying to enjoy it; take this opportunity when it appears.”