The Leeds United right-back has struggled for form of late.
Ayling - who is affectionately nicknamed 'Bill' from his Arsenal days - has been one of Leeds' key players since his arrival from Bristol City in 2016.
But his recent form has dropped below his usual high standards, leading to strong criticism from a section of the Elland Road fanbase.
Several have even called for Ayling to be dropped in favour of Jamie Shackleton, but Bielsa is said to have told Leeds Live the 27-year-old will keep his place against Swansea City on Wednesday.
"For me Bill Ayling is a great player. A complete player. When I say complete, I mean he can manage all the aspects of the game," Bielsa is quoted as saying.
"He can defend as a full-back, as a centre-back. He has an aerial game that is not very common for full-backs. And if we divide the pitch into three segments on the right hand side of the pitch, he defends well, he is very well in playing out, he takes risks when we have to organise and use the ball and the only thing that decreased a little bit is his defensive impact.
"He usually gets a grade about 7 points and now he’s getting a grade of over 6 points.
"The thing we can’t do is to look at everything, so we divide and we command only the last games. The only thing I can tell about Bill Ayling, that he is contributing a little less in attack and usually he was getting a grade of more than 7. Now it’s more than 6.
"But for me he’s a very important player for the team. He is a player that is an example for his team-mates, the public, the fans and in football you have very few players who don’t have ups and downs.
"And when Bill has less impact, he’s always has more than 6 points. Even in his downs he’s over 6 points.
"Maybe I’m not objective. Because I have a very special respect for him, for what he gives to the team. Because he always assumes risks. And because he’s influenced for this feature that I admire him.
"Obviously he’s better than what you think."
Bielsa reportedly confirmed he will make one change to the side that drew 1-1 at Middlesbrough on Saturday, with Pablo Hernandez returning in place of Jack Clarke.
Clarke made way for the Spaniard at half-time last time out, after falling ill, and was later taken to hospital.
And Bielsa is quoted as saying of the youngster: "He’s under observation. We’re doing some more exams to see what happened and we all feel relieved."
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