Tomas Kalas says he returns to Chelsea a better player.

Kalas spent last season on-loan with Vitesse Arnhem.

"I think I have more quality on the ball now," he told chelseafc.com.

"The Eredivisie (the Dutch top flight) is known for football quality and there I learnt a lot, especially in the second year when I was playing right-back because in that position you need more technical skills, but both years were quite successful, I was playing all the games and as player of my age that was the most important thing."