Messi scored twice in that match but was unable to continue his form at Anfield, where the Reds won 4-0.
Asked on Twitter who has been his toughest opponent, Van Dijk picked the little magician.
"There are some difficult strikers out there but probably Leo Messi," Van Dijk said.
The Dutchman was then asked about his favourite career moments, with last season's Champions League final win over Tottenham the pick of the bunch.
He added: "There are a few to mention. Making my debut as a professional footballer, making my debut for the national team, and of course Madrid."