The mercurial Russian was unstoppable, punishing Rafa Benitez's team in a see-saw 4-4 draw. Arsenal fans were in dreamland about what their £15 million winter signing could do.
His first shot came off the underside of the bar and in - always a satisfying sight - to give the Gunners a half-time lead. But nobody could have seen what was to come in an unbelievable second half.
Liverpool deservedly took control at 2-1, only for Arshavin to score twice in three minutes. To equalise, he robbed Alvaro Arbeloa then launched an unstoppable missile past Lukasz Fabianski.
The Pole in goal clearly saw now that Arshavin was playing like Brazilian Ronaldo and Portuguese Ronaldo combined - so just let the 27-year-old's hat-trick goal go right through him without bothering to save it.
Fernando Torres levelled for 3-3 but Arsenal caught Liverpool on the counter on 90 minutes, Theo Walcott racing clear and feeding Arshavin who lashed home his fourth. There was still time for Liverpool to make it 4-4 in stoppage time - but the damage was done.
Benitez's team had battered Manchester United 4-1 at Old Trafford in March to blow the Premier League title race open. But Arshavin had single-handedly dented their terrific run of form.
Arsenal supporters were now drooling over what their new signing - who'd become only the sixth player to score four away goals in a Premier League game - could achieve.
Unfortunately, he'd blow hot and cold for the rest of his time in north London, before returning to Zenit Saint Petersburg in 2012.
There's a strong feeling that Arshavin, an eccentric character who was once photographed leaving a strip club on horseback, did not fulfil his potential - at Arsenal or anywhere.
Still, he clearly has fond memories of his time at the club, as he named his son after Arsene Wenger. And - for one day in 2009 - he did what few players can and proved himself Liverpool's daddy at Anfield.
All imagery: PA Images
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