Romelu Lukaku scored twice as Belgium breezed to a 4-0 friendly win over Saudi Arabia in Brussels, beginning their preparations for this year's World Cup.

Playing for the first time in 2018, Roberto Martinez's men exploited a sub-standard visiting defence and could afford to be wasteful as Lukaku had his brace before half-time.

Belgium remained on top after the break, yet they did not initially look clinical enough in the final third to hand Saudi Arabia a deserved humbling, Michy Batshuayi and Kevin De Bruyne belatedly adding gloss to the scoreline in the closing stages.

This was an opportunity for Martinez to see his best attacking pieces working in tandem - making it a worthwhile run-out - but, even against a World Cup side, this was anything but a test.

Even lowly Group G opponents Panama and Tunisia will not defend with such generosity in Russia come June, making forthcoming friendly fixtures against Portugal and Egypt key.

A lively start saw Dries Mertens, unmarked from a corner, force a first stop from Fawaz Al-Qarni, before a glaring chance fell for Yannick Carrasco from Lukaku's pass, the Dalian Yifang man's tame finish drawing another low save.

It was clear from the off that Belgium had too much pace and power for the opposing back-line, but the visitors - boasting Mohammad Al-Sahlawi, with a joint-best 16 goals in qualifying - offered a threat at the other end, too, and Simon Mignolet was required to parry a Fahad Al Muwallad strike.

Belgium swiftly responded with the opener, though, as a poor pass out from the back gifted the ball to De Bruyne. He quickly fed Lukaku, who had time and space to turn and calmly stroke into the bottom-left corner from 20 yards.

Al-Qarni smothered to deny Lukaku a close-range second from Eden Hazard's cross, but the Manchester United forward doubled his tally before the first half was out. Hazard's jinking run freed his team-mate to roll the ball past a scrambling goalkeeper.