Ramsey's clinical brace added to his goal in the first leg of the tie, and the Arsenal captain believes that the midfielder's excellent start to the campaign is the continuation of impressive pre-season form.
He had a very good pre-season and is now transferring that into our competitive games
"It was brilliant to see Aaron score his two goals," Vermaelen told the official matchday programme.
"Not only is he getting into those positions and finishing well, but his all-round game has improved too. He seems really fit and strong, and he has a great engine. He had a very good pre-season and is now transferring that into our competitive games, and we’re all really happy to see him playing such an important role for us."
That role will be as vital as ever when Tottenham Hotspur come to Emirates Stadium on Sunday. Arsenal's north London rivals are a team that Belgian defender Vermaelen knows well - not least because they now boast three of his compatriots.
"Both sides will be highly motivated and ready to go all out for the three points," he said.
"I know a few of their guys quite well - Jan Vertonghen, Mousa Dembele and Nacer Chadli are all team-mates of mine in the Belgium national team.
"Chadli only joined them recently so will be new to many of you. He is a strong lad, really good technically and a good passer of the ball. He can play on the wing or behind the strikers, and I’m sure he will do well at Tottenham - but we’ll be trying our best to make sure that’s not the case on Sunday."
Read more from Thomas in the Tottenham programme