The Poland international joined Barcelona from Bayern Munich in the summer and has started life in La Liga with five goals in four games.
He carried that fine form into Wednesday's Group C opener with Plzen and showed no mercy.
Franck Kessie gave Xavi's side the lead inside 13 minutes and after that, it was the Lewandowski show.
The 34-year-old received a pass from Sergi Roberto just outside the box and took a few touches to compose himself.
He then let rip with a right-footed effort that whipped past Jindrich Stanek and into the back of the net.
Plzen halved the deficit through Jan Sykora just before the break and for a moment, it looked like they were back in the contest.
That all changed in added time when Lewandowski grabbed his second thanks to some lovely work from Ousmane Dembele on the wing.
Dembele timed a tackle on Jhon Mosquera perfectly to regain possession and he put in a cross that Lewandowski headed home with ease.
Lewandowski completed his hat trick midway through the second half with long-range strike.
LEWANDOWSKI WITH A SECOND GOAL VAMOS pic.twitter.com/ZEAsd9GNcg— Ziad is NOT in pain (@Ziad_EJ) September 7, 2022
Ferran Torres added a fifth shortly after to ensure victory and send Barcelona top of the group.
Fans have reacted to Lewandowski's performance on social media and they're simply in awe.
One person said: "This guy is genuinely something else."
Another put: "Lewandowski is going to feast if he gets the right service at Barcelona."
A third tweeted: "He had to remind Haaland and Mbappe he's still around."
While someone summed it up with: "Let's not forget how good this guy is."
Lewandowski is now the first man in history to score a hat-trick for three different teams in the Champions League.
Next up in Europe's elite competition is former side Bayern and he joked last month he's not ready to face them.
When asked about the reaction he'll get at the Allianz Arena, Lewandowski replied: "I don’t know, I hope [I’m received] positively. I’ll only have positive memories from my time at Bayern. My story with FC Bayern will always remain in my heart."
Featured Image Credit: BT Sport
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