Liverpool were made to work for a 2-1 win over Genk at Anfield, though the result was a key one as the Champions League holders leapfrogged Napoli to top Group E.
Liverpool took a 15th-minute lead through Georginio Wijnaldum, the Netherlands midfielder's first at Anfield since he scored twice against Barcelona in the 4-0 semi-final second-leg comeback in May.
Naby Keita sent James Milner down the left and his cross bounced off a couple of defenders and sat up nicely for Wijnaldum to hook in a shot at the near post with the outside of his right foot.
With a huge game at home to Manchester City at the weekend, this fixture felt even more low-key than a visit by a Belgian club would normally.
However, after Mohamed Salah flashed a shot across goal and wide of the far post, Anfield was stunned into silence when Genk equalised.
Ally Mbwana Samatta got between Alex Oxlade-Chamberlain and Milner to head in a near-post corner five minutes before the break.
Jurgen Klopp made a tactical switch at half-time, moving Salah to the middle, Oxlade-Chamberlain to the left and Origi to the right.
It had the desired effect less than 10 minutes into the second half as Origi's cross was held up and then laid off by Salah for Oxlade-Chamberlain to fire home his third goal against this opposition - and that proved to be the winner.
Additional reporting by PA.
