The hosts came out of the blocks quickly and were almost ahead inside the opening minute when Thomas Olsen swept just over. Yaw Paintsil also dragged a shot just wide, but it was Sociedad who took the lead against the run of play as Mikel Oyarzabal picked out Sergio Gomez, who fired into the top corner.
That sparked the visitors into life, and the same two players combined for a swift second as Oyarzabal cut back for Gomez to score with his right foot this time. Incredibly, Oyarzabal then grabbed his third assist of the first half when he fed Luka Sucic to put Sociedad in cruise control heading into the break.
To their credit, Lillestrom also started fast in the second half, and won a penalty when Jon Martin fouled Gustav Nyheim in the box. Olsen stepped up, but Unai Marrero guessed the right way and pushed it away to restore Sociedad’s three-goal advantage.
The striker was determined to make up for his miss immediately, and glanced a header inches wide before the hour mark.
Yildren Ibrahimaj came even closer just a few minutes later, rattling the crossbar from range. Unfortunately, it was not to be Lillestrom’s night as Sociedad then netted a fourth, with Goncalo Guedes crossing for substitute Orri Oskarsson to tap home his second goal in as many appearances.
Lillestrom were wide open at this point, and after Oskarsson had struck wide, Sucic grabbed his brace and Sociedad’s fifth of the match, matching their goals tally from their win at Malaga last weekend. The ball fell kindly to him in the box, and he calmly slotted home to put some gloss on the scoreline.
There was still time for substitute Arsen Zakharyan to fire in a sixth from distance too, and as a result, Sociedad extend their unbeaten run on their travels to five across all competitions (W4, D1) by picking their first victory of the Europa League campaign.
Meanwhile, Lillestrom’s own four-game undefeated streak in all competitions comes to an end (W2, D2), as they remain winless in the league phase (D1, L2).
Flashscore Man of the Match: Sergio Gomez (Real Sociedad)