World No. 1 Rafael Nadal was pushed in the third set but still rolled into the third round of Australian Open on Wednesday.

The Spaniard dropped only one service game to beat Argentina's Leonardo Mayer 6-3, 6-4, 7-6 (4) in two hours, 39 minutes.

"It was an important victory for me," Nadal said during his on-court interview. "(Mayer is) always a tough opponent. I had to hit some great shots in the tie-break. I'm happy to be in the third round after a while without being in competition."

Nadal, who is now 53-11 lifetime at Melbourne Park, will face Bosnia's Damir Dzumhur in the third round.

Dzumhur, the No. 26 seed, struck 47 winners in beating John Millman of Australia 7-5, 3-6, 6-4, 6-1 earlier in the day.

"Damir has improved a lot (since we played at 2016 Miami)," Nadal said. "He is a tough opponent."

In a late-night second-round match, third-seeded Grigor Dimitrov of Bulgaria advanced with a five-set win over 186th-ranked qualifier Mackenzie McDonald, a former NCAA champion from Los Angeles. Dimitrov defeated the 22-year-old McDonald 4-6, 6-2, 6-4, 0-6, 8-6 at Rod Laver Arena in a match that lasted nearly 3 1/2 hours.

No. 15 seed Jo-Wilfried Tsonga erased a 5-2 deficit in the fifth set pulled out a win over Canadian teenager Denis Shapovalov. The 32-year-old Frenchman emerged with a 3-6, 6-3, 1-6, 7-6 (4), 7-5 decision over the 18-year-old from Richmond Hill, Ontario.

"I'm tired, but really happy," Tsonga said. "I did a big fight today. It's not easy against these young guns, they go for everything, but I just continued to fight."

While Tsonga is playing in his 11th Australian Open, having reached the final in 2008, Shapovalov appeared in the tournament for the first time. However, Shapovalov made it through qualifying for the U.S. Open last summer before knocking out Tsonga, then seeded No. 8, in a second-round match.

In other action Wednesday, Ivo Karlovic of Croatia outlasted Yuichi Sugita of Japan 7-6 (3), 6-7 (3), 7-5, 4-6, 12-10. Karlovic fired 53 aces -- well off the tournament-record 78 aces he produced last year in a win over Argentina's Horacio Zeballos that ended 22-20 in the fifth set.

Karlovic wound up with just 10 double faults Wednesday, four fewer than Sugita, who had 16 aces.

The first two sets featured no service breaks. Sugita lost his final service game of the third set, and Karlovic dropped serve on the last game of the fourth set. The fifth set stayed on serve until Karlovic broke for an 11-10 lead before closing out the win in the next game.

Luxembourg's Gilles Muller, the 23rd seed, also was a five-set victor, 7-5, 6-4, 6-7 (5), 3-6, 6-2 over Tunisia's Malek Jaziri.

American Ryan Harrison pulled off a minor upset when he beat 31st-seeded Pablo Cuevas of Uruguay 6-4, 7-6 (5), 6-4. Harrison, 25, has matched his best Grand Slam performance, when he reached the third round of the U.S. Open last year.

Next up for Harrison is a meeting with sixth-seeded Marin Cilic of Croatia, who had little trouble with Portugal's Joao Sousa, 6-1, 7-5, 6-2.

Elsewhere in second-round matches, 10th-seeded Pablo Carreno Busta was ahead of Gilles Simon 6-2, 3-0 when the Frenchman retired due to a leg injury. Great Britain's Kyle Edmund beat Uzbekistan's Denis Istomin 6-2, 6-2, 6-4; Italy's Andreas Seppi got past Japan's Yoshihito Nishioka 6-1, 6-3, 6-4; and Georgia's Nikoloz Basilashvili defeated Belgian qualifier Ruben Bemelmans 7-5, 6-1, 6-3. Australian Nick Kyrgios, the No. 17 seed, beat Viktor Troicki of Serbia 7-5, 6-4, 7-6 (2).