The Belgian international has tightened up the back four and has forged a formidable defensive partnership with William Gallas.
But Vermaelen is still not happy with his all-round game and feels he can become even stronger.
He said: "I'm not satisfied yet, there are improvements I can make. I am learning from other players and the coaching staff and I want to improve every single day.
"I am very very pleased with my start. But the most important thing is to keep playing like this, and we are still early in a long season."