GENK, Belgium, Nov 9 (Reuters) - Peruvian striker Claudio Pizarro scored a first half hat-trick as Bundesliga strugglers Werder Bremen swept aside Belgium's Genk 5-2 in a UEFA Cup second round second leg on Thursday.

The visitors proved far too strong for the Belgian cup holders, winning 9-3 on aggregate.

After a bright opening as Genk pressed to overturn a 4-1 first leg deficit, Werder took the lead on 24 minutes when Pizarro carved an opening through a sluggish defence to slot past Jan Moons.

The home side struck back immediately with Bernd Thijs striking a free kick through a crowd of players and past an unsighted Frank Rost in the Werder goal.

A third goal in as many minutes saw the visitors regain the lead when Akran Roumani felled Pizarro in the area and the Peruvian coolly converted the spot kick.

Just before the break Pizarro latched on to a loose ball in the area to complete his hat-trick and put Werder 3-1 ahead.

Genk pulled a goal back in the 57th minute when defender Didier Zokora headed home a corner, but the visitors extended their lead on 73 minutes, Paul Stalteri shooting past Moons for his debut European goal.