Reds fans have waited a long time to get a look at the Serbian in a game like this, with manager Jurgen Klopp reluctant to play him despite strong performances for the under-23s.
His performance for Cardiff in their 2-0 defeat perhaps hinted why Klopp has been so cautious, with Grujic struggling to make an impact.
Against Manchester City, this was perhaps understandable, with Pep Guardiola's side in sensational form this season.
Grujic is still getting to know his Cardiff teammates with only one appearance so far previous, and this is his first regular spell of competitive club football since late 2015.
So while there were several mitigating reasons, Grujic will be disappointed he did not put on more of a show.
He played all 90 minutes but did not manage a shot at goal, or create any chances. Grujic's pass completion rate was a disappointing 62 per cent.
Defensively he was more involved, making two tackles and two interceptions, and three clearances.
Grujic is on loan until the end of the season at Cardiff and his quality may only begin to show after a few weeks. Either way this experience against City will have done him good and showed the level he needs to aspire to.
Here is a look at how Liverpool fans reacted on Twitter to Grujic's display...
I think Marko Grujic is the No.6 we've been looking for. Why hasn't Klopp thought about playing him in our midfield 3. #LFC— The Anfield Effect (@AnfieldEffect) January 28, 2018
Can make a tackle,
Play the ball out,
Can dictate tempo.
Incredible defensive display from him so far for Cardiff.
Seen both the games Grujić has played for Cardiff and so far he’s not impressed me at all, know he’s not really played this season but doesn’t look like a footballer so far #lfc— Carl White (@CarlWhite83) January 28, 2018
Grujic starting for Cardiff whilst we sign no Coutinho replacement #LFC— Saph (@saphira_ahmed) January 28, 2018
Well didn't think much of Grujic in the Cardiff game! You'd expect him to be Cardiff's best player if he wants in at Liverpool.— Klopplife (@Welshboy64) January 28, 2018
With Grujic, it’s nice to see him play another 90mins. Although I don’t know whether it might be best to give him a season loan next season or keep him. He definitely needs game time— Aks (@F1ashPoint) January 28, 2018
Great to see Marko grujic get 90mins this evening against city starting to look sharper definitely one for the future for us— shalloelad (@highfieldmush) January 28, 2018
Bring Grujic back!— Aled Jones (@aled37) January 28, 2018