Argentina's Diego Schwartzman saved four match points to upset third-seeded Dominic Thiem 6-4, 6-7 (7/9), 7-5 in the second round of the ATP Montreal Masters. World number 36 Schwartzman seized the initiative against the seventh-ranked Austrian, who fell at the first hurdle after enjoying a first-round bye.
On the defensive early, Thiem held on to level the match at a set apiece on his fifth set point of the second-set tiebreaker. And the 23-year-old appeared to have gained control when he powered to a 5-2 lead in the third set.
But Schwartzman wouldn't go away, saving two match points on his serve at 3-5, another in the next game and yet another as he served to take the set to 5-5. Schwartzman then broke to serve for the match. He fell behind 0-40, but won the last five points of the match for his first win over a top-10 player and a berth in the third round.
Schwartzman's wasn't the only great escape of the day. Canadian teenager Denis Shapovalov saved four match points en route to a three-set victory over Rogerio Dutra Silva in their first-round encounter.
The 18-year-old trailed 4-6 in the second-set tiebreaker but saved all four match points he faced to force a third set. "I don't remember all of them. Honestly, it's a littlebit of a blur," Shapovalov said.
"I remember one of them, he passed me. I hit a pretty tough volley. It was a pretty long point there. On one of them, I remember I was pretty far back. I went for a backhand down the line, which was pretty good. I wasn't holding back. "I just told myself, he's got to win it from me, I'm not going to give it to him. I think I did a good job to stay tough out there."
Shapovalov broke Brazil's Dutra Silva in the seventh game of the third and went on to close out a 4-6, 7-6 (10/8), 6-4 victory. "It's matches like this I live for and that I play for," said Shapovalov, who earned a second-round meeting with former US Open champion Juan Martin del Potro of Argentina.
With old-guard stars Rafael Nadal and Roger Federer taking a day off -- 19-time Grand Slam champion Federer to celebrate his 36th birthday -- Shapovalov was one of wealth of young talents to shine on Tuesday.
South Korean 21-year-old Chung Hyeon withstood 16 aces to beat 2014 semi-finalist Feliciano Lopez 6-1, 4-6, 7-6 (7/3). After the third set went to the tiebreaker without a break of serve, the 56th-ranked Chung built a 4-2 advantage and went on to secure the victory in two hours and 16 minutes.
He next faces ninth-seeded Belgian David Goffin, a 4-6, 6-1, 6-4 winner over Japan's Yuichi Sugita.