![Germany's Alexander Zverev returns to Jack Sock of US during men's single semi-final match at the ATP Stockholm Open tennis tournament in Stockholm on Saturday October 22, 2016. Photo: Soren Andersson / Germany's Alexander Zverev returns to Jack Sock of US during men's single semi-final match at the ATP Stockholm Open tennis tournament in Stockholm on Saturday October 22, 2016. Photo: Soren Andersson /](https://c8.alamy.com/comp/2GJA9YC/germanys-alexander-zverev-returns-to-jack-sock-of-us-during-mens-single-semi-final-match-at-the-atp-stockholm-open-tennis-tournament-in-stockholm-on-saturday-october-22-2016-photo-soren-andersson-tt-kod-1037-2GJA9YC.jpg)
Germany's Alexander Zverev returns to Jack Sock of US during men's single semi-final match at the ATP Stockholm Open tennis tournament in Stockholm on Saturday October 22, 2016. Photo: Soren Andersson /
![Jack Sock of the USA returns to Dustin Brown of Germany during their men's single match at the ATP Stockholm Open tennis tournament in Stockholm Thursday, Oct. 20, 2016. (Fredrik Sandberg/TT via Jack Sock of the USA returns to Dustin Brown of Germany during their men's single match at the ATP Stockholm Open tennis tournament in Stockholm Thursday, Oct. 20, 2016. (Fredrik Sandberg/TT via](https://c8.alamy.com/comp/2P0R976/jack-sock-of-the-usa-returns-to-dustin-brown-of-germany-during-their-mens-single-match-at-the-atp-stockholm-open-tennis-tournament-in-stockholm-thursday-oct-20-2016-fredrik-sandbergtt-via-ap-2P0R976.jpg)
Jack Sock of the USA returns to Dustin Brown of Germany during their men's single match at the ATP Stockholm Open tennis tournament in Stockholm Thursday, Oct. 20, 2016. (Fredrik Sandberg/TT via
![Jack Sock of the U.S celebrates defeating Germany's Alexander Zverev in the men's single semifinal match at the ATP Stockholm Open tennis tournament in Stockholm on Saturday Oct. 22, 2016. (Soren Andersson/TT Jack Sock of the U.S celebrates defeating Germany's Alexander Zverev in the men's single semifinal match at the ATP Stockholm Open tennis tournament in Stockholm on Saturday Oct. 22, 2016. (Soren Andersson/TT](https://c8.alamy.com/comp/2P0R6B7/jack-sock-of-the-us-celebrates-defeating-germanys-alexander-zverev-in-the-mens-single-semifinal-match-at-the-atp-stockholm-open-tennis-tournament-in-stockholm-on-saturday-oct-22-2016-soren-anderssontt-via-ap-2P0R6B7.jpg)
Jack Sock of the U.S celebrates defeating Germany's Alexander Zverev in the men's single semifinal match at the ATP Stockholm Open tennis tournament in Stockholm on Saturday Oct. 22, 2016. (Soren Andersson/TT
![del Potro winner of If Stockholm Open 2016 - Tennis Tonic - News, Predictions, H2H, Live Scores, stats del Potro winner of If Stockholm Open 2016 - Tennis Tonic - News, Predictions, H2H, Live Scores, stats](https://i.ytimg.com/vi/WSNehfIOyYI/maxresdefault.jpg)
del Potro winner of If Stockholm Open 2016 - Tennis Tonic - News, Predictions, H2H, Live Scores, stats
![Dustin Brown of Germany returns to Jack Sock of the USA during their men's single match at the ATP Stockholm Open tennis tournament in Stockholm Thursday, Oct. 20, 2016. (Fredrik Sandberg/TT via Dustin Brown of Germany returns to Jack Sock of the USA during their men's single match at the ATP Stockholm Open tennis tournament in Stockholm Thursday, Oct. 20, 2016. (Fredrik Sandberg/TT via](https://c8.alamy.com/comp/2P0R945/dustin-brown-of-germany-returns-to-jack-sock-of-the-usa-during-their-mens-single-match-at-the-atp-stockholm-open-tennis-tournament-in-stockholm-thursday-oct-20-2016-fredrik-sandbergtt-via-ap-2P0R945.jpg)