Joe Salisbury (foreground), with Rajeev Ram at the net, strikes a forehand back to Matwe Middelkoop and Robin Haase on Friday in Rotterdam.

Robin Haase strikes a forehand as Matwe Middelkoop watches on in Tokyo on Thursday.

Defending champions Roman Jebavy and Matwe Middelkoop advance to the St. Petersburg Open final.

Robin Haase and Matwe Middelkoop take time off on Thursday for some bob sledding at Rellerli.

Robin Haase and Matwe Middelkoop lift their third team trophies of the year in Umag.

Dutch doubles players Sander Arends and Matwe Middelkoop enjoy a day off on Monday in Antalya, riding on jet skis at the Kaya Palazzo Resort.

Third seeds Sander Arends and Matwe Middelkoop enjoyed their day off at the Kaya Palazzo resort after reaching the Turkish Airlines Open Antalya quarter-finals.

Fourth-seeded Matwe Middelkoop and Robin Haase, who triumphed in Pune and Sofia earlier this year, enjoy time in the Palmeraie district with Radu Albot.

Pablo Andujar, Gilles Simon, Matwe Middelkoop, Robin Haase, Radu Albot and Kyle Edmund along with their teams and family enjoy a quad bike session on Sunday in the Palmeraie district.

Gilles Simon with son Timothee, Pablo Andujar, Robin Haase, Matwe Middelkoop and Kyle Edmund listen to a training briefing ahead of their Marrakech quad bike ride.

Gilles Simon with son Timothee, Pablo Andujar, Robin Haase, Matwe Middelkoop and Kyle Edmund take part in a quad bike ride in Marrakech.

Robin Haase and Matwe Middelkoop claim their second ATP World Tour doubles trophy of 2018.

Matwe Middelkoop and Robin Haase earn their first ATP World Tour title as a team, defeating Pierre-Hugues Herbert and Gilles Simon in the Pune final.

Matwe Middelkoop and Roman Jebavy win their first ATP World Tour title together in St. Petersburg.

Matwe Middelkoop and Roman Jebavy topple the No. 1 seeds in the St. Petersburg Open final.

Roman Jebavy and Matwe Middelkoop drop just one set all week en route to the St. Petersburg Open crown.

Matwe Middelkoop celebrates as he win his fourth ATP World Tour doubles title alongside Roman Jebavy in St. Petersburg.

Matwe Middelkoop and Roman Jebavy win their first ATP World Tour title together in St. Petersburg.

Robin Haase and Matwe Middelkoop keep Dutch hopes alive in their Davis Cup World Group Play-off against the Czechs.

Dutch wild cards Wesley Koolhof and Matwe Middelkoop celebrate reaching the Rotterdam semi-finals on Friday afternoon.

Dutchmen Wesley Koolhof & Matwe Middelkoop are all smiles after a first-round doubles win over the Zverev brothers in Rotterdam.

Dutch wild cards Matwe Middelkoop and Wesley Koolhof team up for a first-round doubles win over the Zverev brothers in Rotterdam.

Matwe Middelkoop (left) and Wesley Koolhof saved their best tennis for last in Sydney.

Matwe Middelkoop (izquierda) y Wesley Koolhof ganaron su segundo título de 2016.

Top seeds Wesley Koolhof/Matwe Middelkoop won their second ATP World Tour title of the year on Saturday at the Generali Open in Kitzbuhel, saving a championship point to prevail over wild cards Dominic Thiem/Dennis Novak, 2-6, 6-3 11-9.