Leeds United full-back Stuart Dallas says he will "never have enough words" with which to thank Marcelo Bielsa for transforming his career.
Northern Ireland international Dallas was one of the key men in Bielsa's side as they won promotion to end Leeds' 16-year absence from the Premier League.
The 29-year-old has been converted by the Leeds boss from a winger into an attacking full-back.
"I just wish he had come here earlier than he did," said Dallas.
In an interview with BBC Radio 5 Live's Steve Crossman, he added: "That's no disrespect to the past managers because I have always loved working with whoever has been here, but in terms of my performances he has really improved me.
"I think I speak for 99% of the team when I say that."
Dallas joined Leeds from Brentford in August 2015 and made his Premier League debut against champions Liverpool - the team he supported as a boy - last weekend.
On Saturday, the Whites host fellow newly promoted side Fulham at Elland Road (15:00 BST) in their first top-flight home game since 2004.
"I can't help but think Elland Road would have been sold out two, three or four times over for this game," Dallas added.
"They've waited a long time to get back to this and it is disappointing we can't share this experience with the fans."
Dallas's success with Leeds also saw him approached by Borussia Dortmund striker Erling Braut Haaland for his shirt after Northern Ireland's defeat by Norway earlier this month.
Haaland, 20, was born in the West Yorkshire city when his father Alf-Inge played for United.
"When we swapped shirts he just said 'Marching on Together'," Dallas said in reference to the club's anthem.
"Everyone thinks it is a bit strange he said that but it is because of the connection with Leeds with his father and he wants us to do well.
"He wished me all the best with Leeds and it came as a surprise he wanted to swap shirts with me."
- Listen to the full Stuart Dallas interview during Radio 5 Live's Premier League coverage from 12:00 on Saturday, 19 September