The Egyptian, the current world number 55, began his pursuit of a third ITTF World Tour crown by sweeping aside Alfredas Udra of Lithuania 11-4, 11-6, 11-9, 11-9.

He then proved too strong for Liao Cheng-Ting of Chinese Taipei, though it wasn't until he went a game down until he began to find his rhythm as he eventually sealed a 11-13, 11-6, 11-6, 11-6, 11-5 success.

Second seed Steffen Mengel of Germany was also in ominous form on day one of the main draw as he also picked up two wins to join Assar in the round of 16.

The world number 70 breezed past Gael Vende of Switzerland 11-9, 11-9, 11-4, 11-6 in his opener before he clinched a similarly dominant 11-4, 11-8, 11-3, 11-1 victory against Frane Kojic of Croatia.

Assar will go up against Cedric Nuytinck of Belgium for a place in the last eight, while Mengel is due to face Mihai Bobocica of Italy.

In the women's tournament - where players only had to take to the table once today - Sato booked her spot in the next round with a commanding straight games triumph over Lucie Gauthier of France.

The Japanese was rarely troubled as she ended up on the right side of an 11-7, 11-3, 11-7, 11-7 scoreline.

Sato will meet compatriot Yui Odono in the round of 16.

Elsewhere, two-time European gold medallist Elizabeta Samara of Romania made light work of qualifier Rahel Aschwanden as she set up a meeting with Mariia Tailakova of Russia tomorrow.

Samara didn't quite have it all her own way at times and was tested in a marathon second game before prevailing 11-6, 16-14, 11-4, 11-4.

Action at the ITTF Belgium Open continues tomorrow.