The 22-year-old moved to Cardiff in January last season on loan and played a part in the team's successful promotion to the top flight. Warnock had been confident of getting him back for another season, but he said on Saturday that Grujic is set to remain as part of Jurgen Klopp's squad.
"Grujic looks like he will stay put... I think he would be better off here but it is a contract issue, I understand his point of view," he said, per BBC Sport. "Liverpool have four competitions before Christmas and he can play in those without being named in the 25-man squad."
Grujic was the first signing made by Klopp as Reds boss, as he was confirmed as a Liverpool player in January 2016. Since then, the midfielder has struggled to make an impact, making just eight substitute appearances in the Premier League.
He played 14 times and netted one goal on loan with the Bluebirds last season. Cardiff eventually secured promotion on the final day of the campaign, finishing in second place in the Championship behind Wolverhampton Wanderers.
There was plenty of excitement about Grujic when he arrived at Liverpool, and it would have been expected that he would have made more of an impression in the first team at Anfield by this stage. At 22, this feels like a crucial point in his career.
As noted by Simon Stone of BBC Sport, the player did admit earlier in the window that he was unsure about whether he'd be at Liverpool next season:
Liverpool have strengthened their options in the middle of the park significantly in pre-season, too, with Naby Keita and Fabinho adding strength to the position.
The Reds were well stocked in this area prior to the summer, too. James Milner, Jordan Henderson and Georginio Wijnaldum all enjoyed strong ends to the campaign, while Adam Lallana will be hopeful of rediscovering some form following a 2017-18 disrupted by injuries.
As such, it's tough to see exactly where Grujic fits in for the Reds, with a fitness crisis or a string of suspensions surely required for him to get a sustained run in the first team.