كتب : Hatem Maher
Egyptian right-back Samir created Lierse's opener after just four minutes when his pinpoint cross found Tomasz Radzinski, who slotted home.
Jurgen Cavens doubled the lead eight minutes before the break. Patrick Kabeya-Mbaya notched Deinze's only goal on the stroke of halftime.
The in-form Samir was unlucky not to score the third for Lierse on 59 minutes when his fierce drive struck the woodwork.
The former Zamalek man, who is having a season to remember, scored seven goals so far in all competitions.
Fellow Egyptian Mohamed Abdul-Wahed was included in the starting line-up while Sherif Al-Beyali was introduced ten minutes from time.
Lierse, who aim to seal promotion to the top flight after playing two seasons in the lower division, remained second in the table on 56 points, five behind leaders Sint Truidense.
The league winner directly qualifies for the Belgian first division while teams from the second to the fifth places enter promotion play-offs.