Celtic defender Kristoffer Ajer had a good game in the recent 2-0 win over St Johnstone.
He and fellow centre-back Jozo Simunovic stood up to the Saints attack fairly comfortably.
However, he undone all the good work in injury time.
Ajer miscontrolled a pass, and fouled Callum Hendry, who was through on goal.

He was sent-off, but the Hoops held on for the win.
Ajer now misses Celtic’s upcoming league game against Hibernian.
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Despite the error, Ajer deserves praise for his performance.
Not only against St Johnstone, but over the season.
It’s not been easy for Ajer to establish himself in the first team this season.

Brendan Rodgers has preferred to go with the centre-back pairing of Dedryck Boyaya and Filip Benkovic.
As a result Ajer has been relegated to the status of squad player.
He has mostly played when one of the first-choice duo has been ruled out.
He has coped admirably when thrown in to the side though, and until the recent sending-off hadn’t put a foot wrong this season.
You might not see how important Ajer is to Celtic until next season.
With doubts over the future of both Boyata and Benkovic at the club, Ajer will no doubt have a big role to play in the Champions League qualifiers in the summer.
It is a role he is used to however, as he replaced Boyata in the qualifiers earlier in the season.
Brendan Rodgers will have no doubts turning to Ajer once more in what are some of the most important games of the season.
Despite the sending-off against St Johnstone he has more than earned that right.