CELTIC PARK, Glasgow—What a difference the best player in the world makes. Who would have thought it?

To boil down the contrast between Barcelona’s 0-0 draw with Malaga at Camp Nou on Saturday afternoon and their 2-0 win at Celtic on Wednesday night to the mere presence of Lionel Messi may seem simplistic.

Certainly, it would be ignoring other factors, like the hosts’ game plan not being as quite as miserly as Malaga’s and the return of Luis Suarez.

Factors like this being the first-choice XI bar Andres Iniesta, who is injured, and Jordi Alba’s attacking thrust down the left giving Barcelona an extra outlet they have missed in previous weeks.

But, still, Messi’s influence on this match demands attention. It deserves it.

Celtic were dazzled by the No. 10’s performance.

With the Argentinian falling ill little over an hour before kick-off against Malaga, Barcelona lacked the invention to cut their way through hordes of Malaga defenders crowding their own penalty area.

And when they did get through, finally creating good chances in the final 15 minutes, they found Carlos Kameni in unbeatable form.

Craig Gordon did nothing wrong against Barcelona but still ended up picking the ball out of the back of his net twice. And it was Messi who put it there both times.

The first goal was the perfect illustration of what Barcelona were missing at the weekend but had on Wednesday night.

Neymar had the ball on the left, and the defence seemed well-positioned to keep him at bay.

Against Malaga, with Paco Alcacer up front, the forward couldn’t make the perfect run to give Neymar the passing option. Messi did.

He darted into a zone that made Neymar’s pass hard, but it wasn’t hard enough to push him outside his talent zone. The Brazilian lofted a succulent ball in, and Messi snapped it home brilliantly on the half-volley.

It was a goal that no other team in the world would have scored.

Messi’s second followed from the penalty spot after Suarez was hauled down in the area early in the second half and he dispatched it coolly, for his ninth in the Champions League this season.

Celtic coach Brendan Rodgers had baulked at a question about whether the more believable phenomenon was Messi or the Loch Ness monster in the press conference before the game (“That is the worst question I’ve ever been asked”), but after the game, he was in a more tolerant mood, having been seduced by Barcelona’s No 10.

Would Celtic have won if they had Lionel Messi? That was the question a Catalan journalist posed to the Northern Irish coach in his best English. Rodgers pondered the idea.

“We’d have had a big chance,” he said. "The difference he makes shows. Look at the weekend’s game [against Malaga]. It’s different with Messi, he’s a great, great player, arguably the best who’s ever played football.

"When he plays in your team he makes everyone else better, so if he was playing for Celtic, he would make us better.

"But, yes, he’s phenomenal player, an incredible player and he’s always hungry to score. His first goal comes from that run he makes, very fast. Our players will learn you can’t give that space to a player of that quality.”

The Blaugrana star fired home from the penalty spot.

But beyond his goals, Messi’s quality told. It told in attack, and it told in midfield. It even told in defence, where he worked hard to win the ball back for his team on numerous occasions.

That is one of the positive effects Suarez’s presence has. The striker barrels around up front, hounding defenders. When he works so hard, it makes it much more difficult for the other players in the side to shirk their own responsibilities.

Messi is an extremely intelligent footballer, and when he sees Suarez pressure a centre-back on the ball, his body reflexively prepares itself to intercept a potential pass out to the left-back.

Some of the most memorable moments of the night were Celtic players blaring into challenges on Messi, whose rubber legs wobbled one way before bouncing off in a different direction, leaving his would-be assailant in the mud while he skipped away with the ball.

Even Scottish supporters paid their respects in the latter stages of the game. “Messi, Messi,” chanted Barcelona fans, and a fair few of the public in green and white turned to applaud them. Or, rather, him.

MailOnline reporter Dom King wrote about Messi’s effect on Celtic fans, who generally were in loud, boisterous fashion as they roared their team on.

“We knew Messi’s left boot had many magical qualities, but now it seems to have something else: a mute button. Every time the ball arrived at his twinkling feet, a hush descended over Parkhead in dreaded anticipation,” he wrote.

“Here was another night when he played a different game to those around him.”

Messi worked hard, even defensively.

Spanish media were just as effusive in their praise of the match-winner.

“There is a Loch Ness monster and his name is Lionel Messi,” ran a headline in Sport. “[Build] A statue for Leo at Celtic Park,” cheekily mooted Mundo Deportivo.

As Real Madrid received the news on Thursday morning that one of their finest players, Gareth Bale, would be out for the Clasico and beyond, it contrasted violently with the ripples of joy sent out by Messi, who provided warmth and nourishment on a bone-chilling night in Glasgow.

This was precisely what Barcelona needed ahead of the trip to Anoeta on Saturday to face Real Sociedad. It is a ground they have not won at since 2007.

Facing the fire offered by a charged-up Scott Brown plus around 60,000 Celtic fans and putting it out is the perfect morale boost before they travel to San Sebastian.

The wintry Basque Country won’t seem quite as cold after this. The cliched talking point is if Messi could hack it on a cold midweek evening at the Britannia, something performances like this pour scorn on, from a great height.

Because that is where Messi operates, on planes of thought that few can countenance, let alone clamber up to.

Rik Sharma is Bleacher Report’s lead Barcelona correspondent. All information and quotes obtained firsthand unless specified. Follow him on Twitter here: @riksharma_.