Momen, the world number three, won 11-9, 12-10, 11-5 at the Khalifa International Tennis and Squash Complex.

"It was very close, with the first two games going down to the wire and you never know what could have happened if the score was reversed," the victorious Egyptian said.

"I am very happy with the way I carried out my plan today. 

"It is the best you can do against Mazen because sometimes he comes up with some unbelievable stuff that no matter what you plan for, you might as well cancel it immediately."

Momen will face Abdulla Mohd Al Tamimi in the next round after the Qatari became the first player from the country to reach the last 16 at the World Championship.

Al Tamimi stunned France's Mathieu Castagnet, the former world number six, 12-10, 11-8, 11-8.

Sixth seed Diego Elias of Peru battled into the third round as he needed five games to get past Scotland's Greg Lobban.

Elias earned a 6-11, 11-3, 11-4, 9-11, 11-4 victory to edge past his Scottish opponent, who threatened to cause a huge upset.

Germany's Simon Rösner, seeded fifth, is also through after he overcame England's Declan James 11-9, 9-11, 11-8, 11-9.

Third seed Karim Abdel Gawad also dropped a game before beating Mexico's Cesar Salazar 10-12, 11-6, 11-5, 11-7.

The tournament continues tomorrow.