There was barely a hint of a smile when he scored the first goal, probably because he was still thinking about how many he could have scored if he'd been on the pitch for the previous 76 minutes.
Then with the next two strikes the grin grew broader, before Mohamed Salah was finally beaming as he clung onto Harvey Elliott during the long wait for the teenager's first ever Champions League goal to be confirmed by VAR.
Salah enjoyed himself in Glasgow, eventually, as he doubled his tally of open play goals for the season in just six minutes, taking the score from 3-1 to 6-1 and crushing a Rangers side who started with such promise but ended broken, battered and beaten by seven goals to one.
Salah can do that to you, or at least he used to.
The Egyptian has been below his dazzling best since the second half of last season when he returned to Liverpool after heartbreak in the final of the Africa Cup of Nations, with everything that has happened to the Reds since viewed through the prism of his performance and, on the grandest stages, his despair.
It was he, after all, who thought he might have secured the Premier League title on the final day of last season when he scrambled the ball over the line against Wolves and wheeled away in jubilant celebration, only for Liverpool's players to be informed by those on the Kop that Manchester City had come from two goals down to lead against Aston Villa.
And then there he was in Paris, after some bullish talk beforehand, being repeatedly denied by Thibaut Courtois on a night which started with such hope for Liverpool but descended into regret on the pitch and outright concern off of it. If you're looking for a cause of a hangover for Liverpool as a club this season, then that is it.
As a team though, well some of those problems have been self-inflicted.
Jurgen Klopp's attempt to remodel his side following summer departures and arrivals has seen him station Salah in a much wider position than we're used to seeing him in, even if the German rejected this notion earlier in the season.
Some of his displays have still been okay, and his often overlooked playmaking abilities have been evident, but is this really the right way for Liverpool to once again keep pace with the relentless Manchester City and their new goal cyborg upfront?
Sure he dipped a little last season, but do you sacrifice Salah's goals - or, more importantly, the setup that gets him in the positions to score those goals - just to make life easier for Darwin Nunez? Or to give Elliott a sturdier platform upon which to develop his obvious talents? Or to cover up the lack of quality and available bodies in midfield?
Darwin and Elliott are supremely talented players, and the confidence both will gain from goals in Glasgow could be vital as they look to kick on, but both would still surely agree that Salah should be treated as a priority within the squad. He's got a new contract that almost demands as much these days.
The new deal signed in the summer was beginning to be viewed with suspicion by some as Salah failed to hit the heights scaled previously, with the mischievous looking towards that now infamous Pierre-Emerick Aubameyang deal at Arsenal as evidence of what can happen when the star man gets what he wants.
As with so much at Liverpool though, it is the teething process of an often malfunctioning system which is largely to blame for individual issues such as Trent Alexander-Arnold's defending or a midfield off the pace. Salah hasn't been scoring goals because he hasn't been in the positions to.
Until Wednesday night.
“A different position, more inside," said Klopp with one of those half-smiles of his when first asked about Salah's display by BT Sport after the match at Ibrox. There was then one of his quick, one breath laughs, almost as if he knew that he could have done with the star man at his club in those positions earlier in the season.
Salah would touch the ball just nine times in Glasgow, but six of them would come within the penalty area and three of them ended with him putting the ball in the back of the net, with those three strikes coming within six minutes and 12 seconds of each other to set a new Champions League record for a quickest treble.
“We all know when it is running for Mo he is absolutely exceptional," continued Klopp. "I hope everything works for him from now on, like I hope it does for us.”
The fact that it hasn't been working is partly down to the system the manager has placed him in though, with Sunday at Arsenal another example of what happens when he is stationed too wide and unable to influence the game in central areas, where Darwin, Diogo Jota and later Roberto Firmino were placed.
Much was made of Klopp bringing Salah off in that match, with Arsenal's Takehiro Tomiyasu also coming in for praise for how he dealt with him, but in truth the manager had got himself in such a muddle with his setup that by the end Jordan Henderson was playing wide right in a 4-4-2, something Liverpool fans hadn't seen for nigh-on 10 years.
Klopp has to look at himself for some of the issues at Liverpool this season, and for not providing a platform for the likes of Salah to shine, but here everything looked perfectly set up for the Egyptian, who had Jota feeding him passes - three of them for his goals - and Elliott wider on the right.
That allowed him to get into that channel on the right side of the penalty area where he is so, so dangerous, and from where so many of his Liverpool goals have been scored.
All three strikes were signature Salah, as Rangers defenders dare not touch him and goalkeeper Alan McGregor - superb at Anfield last week - couldn't adjust himself for the split second that Salah would shoot because he didn't know it was coming.
None of the goals matched the swagger of that strike against Manchester City last season because barely anything does, but there was a hint of them there, and with City on the horizon at the weekend that could not be coming at a better time for Liverpool.
The Reds have been rocking and rolling for much of the season, but getting Salah into the positions to deliver will undoubtedly get them on a steadier course. That is a guarantee.
Klopp must surely know it, and if he didn't then he's just been given a golden reminder.
