Witsel signed a four-year deal with Dortmund after agreeing a move from Tianjin Quanjian in August and has made an immediate impact.

Dortmund's fine form has it four points clear atop the table with Witsel among the league's most reliable midfielders, having completed 92.5 per cent of his attempted passes in the Bundesliga.

Witsel, who set up Paco Alcacer for Dortmund's winner against Bayern Munich, is sure he made the right call in leaving the Chinese Super League.

"Switching to BVB was the best career decision I've ever made," the Belgium international told Bild. "I have never played with better players than here.

"Besides, the location is ideal. My family and I are now in close proximity to our homeland."

Witsel was inspirational in the Klassiker with an all-action display capped with sending Alcacer through for a superb winning goal in a thrilling 3-2 success.

The former Zenit midfielder does not think Dortmund should get carried away with title talk despite having a seven-point cushion over Bayern.

"Just because we beat Bayern, we will not speak of the championship," Witsel said. "We would do well to continue focusing on the coming weeks."

Witsel made his 100th international appearance as Belgium beat Iceland 2-0 in the Nations League on Thursday.

Roberto Martinez's men must avoid defeat away to Switzerland on Monday (AEDT) to secure a place in the finals.