Charlie Mulgrew has revealed that a pre-season game between Celtic and Crewe Alexandra was the moment he realised Virgil van Dijk was the real deal.

Mulgrew spent time at Celtic as a youth before returning to Glasgow in 2010, becoming a no-nonsense defensive player that was used both in the middle of the park and at the back. He had solidified himself in the squad when a young Van Dijk signed for Celtic, and was impressed with the Dutch defender's performances in the east end of Glasgow during his two-year spell.

Speaking on the Undr the Cosh podcast, the 38-year-old named the moment that he saw the quality of Van Dijk - and it was actually a pre-season friendly played behind closed doors against Crewe. His first day, he strolled forward with the ball, his first day, I'll never forget it," Mulgrew recalled. "PS2.5m from Groningen we paid for him. There were a lot of signings like that at Celtic. It was a toss of a coin, what you were getting. But he looked the part, but then you never know.

"He strode forward with a game against Crewe. It was at the training ground and Crewe had come up for a pre-season friendly. He strode forward and hit the ball from about 35 yards off the underside of the bar, and you were thinking, 'this guy's alright'. And he was brilliant."

Mulgrew also noted that the Dutch international learned an early lesson at Celtic during a Champions League qualifier against Shakhter Karagandy, where the defender struggled against their strong striker.

"So this was the thing, he was used to playing in Holland and having a lot of the ball and probably a lot of it on the ground, and all of a sudden we went there and it was just banging the ball long. But he learned his lesson well because he never played the return leg and then he obviously never left the team after that."

After winning two Scottish Premiership titles and one League Cup with Celtic, Van Dijk made a PS13million move to Southampton - where he caught the eye of Premier League giants Liverpool.

Van Dijk recalls his time at Celtic fondly, as he told The Rest is Football podcast: "It was time for me to make that the next step. I left with my wife at the moment and obviously things are different. You are away from your family, you are on your own, it's a different culture and language.

"But it's not crazy different as Scotland and Holland is not like five or six hours away from where you lived before, but it was definitely a big change. We had our first kid in Glasgow and we really enjoyed it over there. It prepared me for what came next."