The talented midfielder has become a key figure at Celtic Park with his stock rising further following his last-gasp winner over Kilmarnock in the last encounter leading up to Saturday’s match.
Therefore supporters were probably shocked to see him replaced at half-time against Hearts with the team leading 2-1, especially as his driving runs had made a significant impact.
Deila, however, explains how the Australian was suffering from dizziness and was in little shape to continue, though it’s not thought to be anything serious as the club await further checks.
“Tom Rogic was dizzy on the pitch so I had to take him off. We’ll see tomorrow, but I think he’ll be okay,” the Celtic boss explained to reporters for the Scottish Sun.
"This was a big, big win for us today. It was a tough game, good opponents and it gives us a lot of confidence going into Tuesday’s game."
Rogic joined Celtic from Central Coast Mariners in the winter of 2013 and made his first start for the club earlier this season after enjoying a decent spell out on loan with Melbourne Victory.
The 23-year-old has gradually become an regular feature in the Hoops’ midfield, starting 21 Scottish Premiership matches this term and scoring an impressive seven goals.
Celtic will want him back fit for the midweek trip to Dundee before facing Motherwell away at the weekend, two games which would go far in determining Celtic’s stronghold at the top of the table.