Manager Martin O'Neill's decision for the matches against St Johnstone and Rangers initially seemed prudent but ultimately backfired with a 3-0 defeat at Ibrox and Johnstone struggling mightily.

Sinisalo was then promptly restored to the starting line-up.

The Finnish keeper, who joined Celtic from Aston Villa in the summer of 2024, admitted he was taken aback by the decision to leave him on the bench at McDiarmid Park.

Sinisalo said: "I'll put it bluntly, it was a surprise but that's ultimately a decision that's been made.

"That's gone now, you can't really focus on it too much.

"It's down to me in terms of staying in the team.

"Like I said, performing in a manner that there isn't a conversation.

"I don't want there to be a conversation, that's the bottom line."

Sinisalo took over from Kasper Schmeichel as Celtic's number one last season, playing a key role in his team's unexpected domestic double victory.

The 25-year-old has yet to make any mistakes leading directly to goals, proving his reliability between the posts.

He added: "I've waited a long time and worked hard and played a lot of games now.

"Once you get a bit of taste of that, you don't want to let it go.

"It's what you want to do.

"It gives you that little fire in the belly and kind of say, this is my time now and I want that time to be now."

Despite his surprise at losing his place to Johnstone, Sinisalo maintains a good relationship with his fellow keeper, having known him for nearly a decade.

He recalled: "It's funny because I was actually on trial as a 15-year-old when he was the number one at Aston Villa, on loan from Man United at the time.

"I trained with him when I was 15, before I even signed for Villa."

Sinisalo revealed a mutual respect between the two: "When I'm playing, he's there supporting me like everyone else is.

"We're so privileged in a way to be such a tight-knit group as goalies.

"It's so important it stays that way."

Sinisalo conceded five goals in Celtic's last European trip but saved a penalty in the same match against LASK.

Looking ahead to Thursday's match against Benfica, he is optimistic but realistic.

He said: "We're facing a very good team here.

"They're a team full of internationals that not just get picked for their countries, they start for their countries and they're not just small footballing nations.

"It's a good side, but it's a game that you can really enjoy and relish.

"In a way, raise your levels.

"There's no better place to do that.

"Sometimes games like that force you to do that if you want to get something out of it."

He also believes that the team can learn from past successful matches: "We're looking forward to it and maybe we can have a little think on what we've done well in Stuttgart or Feyenoord.

"I think Bologna as well, where we obviously went a man down, but we've played some really good stuff and defended well as a team because we're going to have to defend at times."

Sinisalo's determination and optimistic outlook bode well for his future at Celtic, both in domestic and European competitions.