The talented defender came on against St Johnstone.
Celtic have already won the Scottish Premiership ahead of their final game of the season against Motherwell on Sunday.
With that in mind it gave Celtic boss Ronny Deila, who will be leaving the club at the end of this season, a chance to give a youngster a go in the first-team.
The player in question was Anthony Ralston.
He came on for Saidy Janko in the fixture with 16 minutes left, to earn his Celtic debut.
Now, with Celtic preparing for the weekend, Ralston was pictured in training again today as he looks to make his second appearance for the club – as shared by Celtic’s official Twitter account:
It's back to the training pitch for 17-year-old Anthony Ralston who made his first-team debut in last night's game. pic.twitter.com/0BivneVYyF— Celtic Football Club (@celticfc) May 12, 2016
The 17-year-old defender is certainly looking a hit prospect for the future at Celtic and impressed earlier in the season during a loan spell with Queen’s Park.
He played 14 times for the Hampden Park side this season, scoring one goal for the club.
Celtic have already seen one young full-back come through the youth ranks to thrive this season in left-back Kieran Tierney and Celtic fans will be hoping that Ralston has a similar rise to prominence at Parkhead.