Last October, Cristiano Ronaldo admitted that former Arsenal and Chelsea defender Ashley Cole was the toughest opponent he has ever faced.

"Over the years I had some great battles with Ashley Cole, he does not give you a second to breathe," Ronaldo told Coach Mag, per Sky Sports

"He was such a tenacious player when he was at his peak, quick, tough in the tackle. You knew it would never be an easy game."

It’s a testament to Cole’s ability that Ronaldo, one of the greatest footballers in history, rates him so highly. There’s even a theory - albeit a light-hearted one - that five-time Ballon d’Or winner only started playing on the right just to get away from Cole.

The pair went head-to-head on several occasions during Ronaldo’s six year spell at Manchester United, and they also met on international duty.

The Portuguese star has since gone on to test himself against the likes of Jordi Alba and Filipe Luis in Spain, but Cole tops the lot in his opinion.

Cole's complete performance vs Ronaldo

One such performance perhaps explains why Ronaldo rates Cole, who currently played for Los Angeles Galaxy, so much. It came in November 2006, when Chelsea held Man United to a 1-1 draw at Old Trafford.

We’ve uncovered a video of Cole’s performance, featuring analysis from Ian Wright. Any aspiring full-back should definitely take a look.

Go to 1:00 to watch Cole mock United supporters by gesturing how he had Ronaldo in his pocket.

Ronaldo once embarrassed Cole

Cole didn’t always have the upper hand against Ronaldo, mind. Remember the time the Portugal international completely embarrassed him with one slick skill?

Ouch.

But on the whole, Cole can be proud of his performances against the Madrid star. Plenty more have certainly come off worse.

Legend

Cole is widely-regarded to be the best left-back in Premier League history, but Liverpool hero Steven Gerrard went as far as to call him the best left-back on earth.

Gerrard posted a picture of the two on Instagram in November, adding the caption: "Best left back on earth #trustme".

Arsenal fans, of course, don't share such touching sentiments towards the left-back. Cole left the Gunners in 2006 after receiving an improved wage offer from Chelsea and went on to enjoy eight successful years in west London, winning one Premier League title, the Champions League and four FA Cups.

Yet despite the sorry end to his Arsenal career, Arsene Wenger admits his departure is one of his regrets in management.

"A regret of my career," Wenger said in a book about Arsenal's 2003-04 Invincibles, via The Guardian.

"He left on a misunderstanding between his agent and the club. A fantastic fighter as well. The rest of his career has shown how big a player he is. It should have been here."

Is Ashley Cole the best left-back in Premier League history? Let us know in the comments section below!