STOCKHOLM, October 19, 2016

The first round of the If Stockholm Open concluded on Wednesday, highlighted by Juan Martin Del Potro, who has returned to the Swedish capital for the first time since 2011. The 28-year-old Argentine entered the main draw with a wild card and ousted US-American John Isner 6-4, 7-6.

Del Potro withstood 15 aces, hitting nine of his own to celebrate his first win in Stockholm after one hour and 29 minutes. The world number 63 will next take on Nicolas Almagro from Spain.

Last year’s runner-up and sixth seed Jack Sock fought past Malek Jaziri, winning 3-6, 6-3, 7-5. The 23-year-old from the United States saved eight of the 11 break points he faced, converting three of his own to finish the encounter after two hours and 17 minutes. Next up for Sock will be Germany’s Dustin Brown.

Second Round Wins For Karlovic And Zverev

Alexander Zverev

The second round also started on Wednesday with the tournament’s number three Ivo Karlovic beating Swedish teenage wild card Mikael Ymer, rallying 4-6, 6-4, 6-4. The big-hitting Croat sent down 16 to advance in one hour and 47 minutes. Karlovic is eyeing another serving milestone, now being only nine aces away from reaching 1,000 this season. Since 2007, the 37-year-old Zagreb native has led the ATP World Tour in aces five times (2007-09 and 2014-15). Karlovic now awaits the winner of the Almagro and Del Potro encounter.

Fourth seed Alexander Zverev defeated Adrian Mannarino of France in the final match of the day 7-5, 6-4. The German teenager, who will end his season after this week, converted three of his eight break point chances to set a quarterfinal meeting with either Tobias Kamke or Radu Albot.