Mate Pavic and Nikola Mektic receive the year-end No. 1 doubles trophy at the Nitto ATP Finals on Sunday.

Mate Pavic and Nikola Mektic celebrate beating Kevin Krawietz and Horia Tecau on Sunday at the Nitto ATP Finals.

Mate Pavic and Nikola Mektic were presented with the year-end No. 1 doubles trophy on Sunday at the Nitto ATP Finals.

Top seeds Nikola Mektic and Mate Pavic beat Kevin Krawietz and Horia Tecau in the Green Group on Sunday at the Nitto ATP Finals.

Mate Pavic and Nikola Mektic defeat Marcelo Arevalo and Matwe Middelkoop in straight sets to reach the quarter-finals at Indian Wells.

Top seeds Mate Pavic (left) and Nikola Mektic succumb to wild cards Jackson Withrow and Nathaniel Lammons in the first round of the 2021 US Open.

Nikola Mektic and Mate Pavic will be aiming to win a fourth ATP Masters 1000 title on Sunday in Toronto.

Croatians Mate Pavic and Nikola Mektic defeat countrymen Marin Cilic and Ivan Dodig on Friday to win the gold medal in Tokyo.

Nikola Mektic (right) and Mate Pavic became the first all-Croatian team to win the Wimbledon doubles trophy on Saturday.

Nikola Mektic and Mate Pavic defeat Rajeev Ram and Joe Salisbury on Thursday to reach their first Wimbledon final.

Nikola Mektic and Mate Pavic celebrate winning the Rome doubles title on Sunday over Rajeev Ram and Joe Salisbury.

Nikola Mektic and Mate Pavic captured their third ATP Masters 1000 trophy of 2021 in Rome on Sunday.

Mate Pavic (left) and Nikola Mektic (right) celebrate winning the Monte-Carlo doubles title on Sunday.

Mate Pavic (left) and Nikola Mektic (right) celebrate capturing the Monte-Carlo doubles title on Sunday.

Mate Pavic (left) volleys during the Monte-Carlo final, which he won with Nikola Mektic on Sunday.

Nikola Mektic and Mate Pavic took a 3-0 lead in the first set of the Monte-Carlo doubles final against Daniel Evans and Neal Skupski on Sunday.

Mate Pavic (left) and Nikola Mektic (right) reach the Monte-Carlo doubles final on Saturday.

Nikola Mektic and Mate Pavic beat Daniel Evans and Neal Skupski to triumph in Miami for their fourth title of the season.

Mate Pavic and Nikola Mektic break serve three times against Daniel Evans and Neal Skupski on Saturday to win the Miami title.

Nikola Mektic (right) and Mate Pavic (left) own a 22-3 record this year.

Second seeds Nikola Mektic (left) and Mate Pavic (right) book their places in the Dubai semi-finals on Thursday.

Nikola Mektic (right) and Mate Pavic (left) capture their third title of 2021 on Sunday at the ABN AMRO World Tennis Tournament.

Nikola Mektic (right) and Mate Pavic (left) have reached the semi-finals or better at all four events they have played in 2021.

Mate Pavic (left) and Nikola Mektic (right) win their 14th match in 2021 on Friday for a place in the Rotterdam semi-finals.

Second seeds Mate Pavic and Nikola Mektic improve to 13-1 on the season after beating Robin Haase and Matwe Middelkoop on Tuesday in Rotterdam.