The 23-year-old attacker has already netted nine goals in 12 appearances in all competitions this term, six of which came after Messi sustained a serious knee injury against Las Palmas back in September.
Vermaelen has stressed Barcelona are obviously missing Messi, but is delighted with the way Neymar has stepped up his game.
"I think Neymar is playing very well this season, scoring a lot of goals," the Belgian defender said at a news conference.
"Of course, we're missing Leo the last couple of games, and I would rather have him on the pitch than off the pitch, because I think he is the best in the world.
"But, we have other players who can make the difference. We have a lot of players with quality. We have good depth in our squad, and Neymar is one of them. He steps up.
"The last couple of games he's been very important for us and very decisive, so he's very important for us at the moment."
Neymar will be looking to add to his tally on Wednesday when Barcelona take on BATE in the Champions League. The former Santos star set up both of the Catalans' goals in the 2-0 away win on matchday three.
