Novak Djokovic was made to work hard for his 18th consecutive victory, eventually putting away Tomas Machac in the first round of the Dubai Tennis Championships.

Djokovic, who is celebrating a record 378th week as world number one, had to rely on a third-set tie-break to finally get over the line, defeating his Czech opponent 6-3 3-6 7-6 (7-1) on Tuesday.

Machac is ranked 130th in the world, but caused Djokovic plenty of problems, earning 10 break points across the match, though he was only able to convert three.

Djokovic had a 4-1 lead in the deciding set before Machac fought back to force a tie-break, but the Australian Open champion ultimately had few problems at 6-6 as he won seven of the eight points played to clinch the win.

"Tomas certainly didn't play like the No. 130 in the world today," Djokovic said of his opponent. "He was giving me all kinds of trouble. But I guess when it mattered, I found another gear."

Djokovic, who is still undefeated in 2023, will face Tallon Griekspoor in the second round.

Elsewhere, fresh off two titles in as many weeks, third seed Daniil Medvedev eased past Matteo Arnaldi 6-4 6-2 to tee up a tie with Alexander Bublik next after his opponent Alexandar Lazarov retired hurt with Bublik leading 6-1 1-0.

Felix Auger-Aliassime defeated Maxime Cressy 7-6 (7-4) 3-6 6-3, but sixth seed Karen Khachanov is out after he was beaten 7-5 6-2 by Botic van de Zandschulp.

The Dutchman will take on Mikael Ymer in the second round after his 6-2 6-3 win against Francesco Passaro, while eighth seed Borna Coric and Dan Evans played just four games before the latter retired hurt.

Christopher O'Connell set up a match against Alexander Zverev in the next round after he overcame Emil Ruusuvuori 7-5 6-4.

Fifth seed Hubert Hurkacz, meanwhile, came from behind to edge past world number 119 Alexander Shevchenko with a third-set tie-break. The Pole prevailed 3-6 6-3 7-6 (9-7).