World no. 4 Dominic Thiem will have to wait until March to move in front of Roger Federer and crack the top-3 for the first time, losing in the quarter-final of Rio de Janeiro to a qualifier Gianluca Mager 7-6, 7-5 in an hour and 55 minutes, staying 85 points behind the Swiss on the ATP list.
Two-time Roland Garros finalist was far from his best this week, struggling with a small knee injury and overcoming Felipe Meligeni and Jaume Munar to reach the quarters somehow, moving a win away from a career-high ranking.
Nonetheless, Mager emerged at the top after two days of tennis due to rain delays, prevailing in the crucial moments to find himself in the first ATP semi-final, heading to Rio de Janeiro with two ATP triumphs under his belt.
Serving at 77%, the Italian fended off five out of seven break chances and earned three breaks to emerge at the top and reach the last four after firing 35 winners and 27 unforced errors. Ready to challenge much better-ranked opponent, Gianluca broke Dominic for a 3-1 lead on Friday, forging the advantage that Thiem erased with a break at love in game seven, with both players serving well to set up a tie break that the Italian won 7-4 after two mini-breaks.
The outsider grabbed another break in the third game of the second set when they had to go away from the court due to rain, not being able to resume the clash and getting back on Saturday for more exciting action. Thiem saved a break chance in game seven with a service winner but couldn't create any advantage on the return until game ten when Mager served for the win.
The nerves started to show up and the Austrian grabbed the break that kept him alive, giving him a massive boost that gave him nothing after all, with Gianluca placing a forehand winner for another break in game 11, serving for the win for the second time.
Ready to avoid the same mistakes, the Italian landed an ace for a hold at 15 that propelled him into the semis where he will have a chance even to reach the final later today.