Celtic winger Mikey Johnston was disappointed to miss Scotland Under-21s' victories over San Marino and Croatia with a groin injury but insists he is focusing on returning to full fitness as soon as possible.

The injury, which he sustained in Celtic's 2-0 derby win against Rangers, will keep him out for Saturday's trip to Hamilton but he hopes to be back in action sooner rather than later.

"I've just got a groin strain so I'll miss the weekend's game but I'll hopefully be back after that," said Johnston, speaking at the launch of the SPFL Match Attax 2019/20 trading card game.

"I was buzzing when I saw the result (against Croatia) last night. I was a bit disappointed that I was out of it but I'll hopefully try to get back fit as quickly as possible."

Johnston has made a bright start to the current campaign for Celtic, contributing four goals in 10 matches in all competitions so far.

He is pleased with how both he and Neil Lennon's side, who have a 100 per cent record from their opening four league games, have started the season.

Johnston added: "I think it's been a good start. Obviously it's disappointing not getting into the Champions League for everyone involved.

"But I think it's been a good start. Obviously beating Rangers was a high.

"I'm delighted that the manager has shown a lot of faith in me and given me games.

"I'm enjoying every minute of it.

"I think I've got to keep playing well to keep my place because there is always someone who is doing well who could come into the team and replace you.

"There's healthy competition for everyone so it's just something you've got to deal with.

"I think everyone's got to earn their place and, if I'm not playing well, then I'm not going to play.

"But if I keep producing, scoring goals and getting assists then hopefully I'll play."

:: Mikey Johnston was speaking at the SPFL Match Attax 2019/20 launch – for more news and info follow @ToppsMatchAttax on Twitter and Facebook, @toppsmatchattax_ on Instagram and subscribe to MatchAttaxOFFICIAL on YouTube