Belgium's Davif Goffin (2nd R) , Pierre-Hugues Herbert (R) of France, Robin Haase (L) and Matwe Middelkoop (2nd L) of the Netherlands pose with their trophies after the ATP Qatar Open Tennis tournament doubles final at the ATP Qatar Open Tennis tournament in Doha, capital of Qatar, Jan. 4, 2019. (Xinhua/Nikku)

Robin Haase (L) and Matwe Middelkoop of the Netherlands pose with the trophy after the doubles final match of ATP Qatar Open Tennis tournament against Robin Haase and Matwe Middelkoop of the Netherlands in Doha, capital of Qatar, Jan. 4, 2019. (Xinhua/Nikku)

Pierre-Hugues Herbert of France (R) and David Goffin of Belgium pose with the trophy after winning the doubles final match of ATP Qatar Open Tennis tournament against Robin Haase and Matwe Middelkoop of the Netherlands in Doha, capital of Qatar, Jan. 4, 2019. (Xinhua/Nikku)

Robin Haase (R) and Matwe Middelkoop of the Netherlands compete during the doubles final match of ATP Qatar Open Tennis tournament against Robin Haase and Matwe Middelkoop of the Netherlands in Doha, capital of Qatar, Jan. 4, 2019. (Xinhua/Nikku)

Robin Haase (R) and Matwe Middelkoop of the Netherlands react during the doubles final match of ATP Qatar Open Tennis tournament against Robin Haase and Matwe Middelkoop of the Netherlands in Doha, capital of Qatar, Jan. 4, 2019. (Xinhua/Nikku)

Pierre-Hugues Herbert of France (L) and David Goffin of Belgium react during the doubles final match of ATP Qatar Open Tennis tournament against Robin Haase and Matwe Middelkoop of the Netherlands in Doha, capital of Qatar, Jan. 4, 2019. (Xinhua/Nikku)

Pierre-Hugues Herbert of France (L) and David Goffin of Belgium pose with the trophy after winning the doubles final match of ATP Qatar Open Tennis tournament against Robin Haase and Matwe Middelkoop of the Netherlands in Doha, capital of Qatar, Jan. 4, 2019. (Xinhua/Nikku)

Pierre-Hugues Herbert of France (L) and David Goffin of Belgium celebrate during the doubles final match of ATP Qatar Open Tennis tournament against Robin Haase and Matwe Middelkoop of the Netherlands in Doha, capital of Qatar, Jan. 4, 2019. (Xinhua/Nikku)

Pierre-Hugues Herbert of France (R) and David Goffin of Belgium celebrate after winning the doubles final match of ATP Qatar Open Tennis tournament against Robin Haase and Matwe Middelkoop of the Netherlands in Doha, capital of Qatar, Jan. 4, 2019. (Xinhua/Nikku)