The Barcelona striker capitalised on an error by Saudi Arabia midfielder Abdelulelah Al Malki before sending a composed finish past onrushing goalkeeper Mohammed Al Owais.
Lewandowski was visibly emotional after ending a run of four World Cup games without finding the net.
Piotr Zielinski had given Poland a first-half lead from Lewandowski's cutback, but Saudi Arabia were awarded a penalty five minutes later for Krystian Bielik's...
