The Whites midfielder is expected to start in a game that will decide Poland s fate in Group E.
Sweden sit top going into the last round of fixtures before the knockout stages, having taken four points from the first two games, and have already qualified for the last 16 whatever happens today, while the Poles are bottom with a single point.
The permutations for Group E are complicated but the task for Klich and Poland is simple - they must win, whatever happens in the other game between Spain and Slovakia.
Klich started both of the opening two games, making his major tournament debut at the age of 31 in the 2-1 defeat to Slovakia.
If anyone is built for the rigorous demands of tournament football it's the man who played 93 of Marcelo Bielsa's first 94 Championship games at Leeds United.
In the Premier League last season he started just 28 of the 38 fixtures but failed to feature in only three and for two of those he was given time off by Bielsa in order to allow him to end the season on a high and keep him fresh.
Ahead of his third Euro 2020 game in nine days, Klich is still feeling fresh.
"I like short breaks," he said.
"I could only play matches and not train at all. No problem for me. I've made a lot of appearances this season and I know how I should recover. Physically there is no difference between playing for the national team and playing for the club. Of course, it all depends on how much and how you run. But I feel fine. I like to play every three days and that suits me."
Another man feeling fresh, having not yet played at this summer's tournament, is former Leeds defender Pontus Jansson.
Klich hopes the centre-half is in the Sweden line up this evening.
"I wrote to him under his last post on Instagram Stories that I hope he won't be in the match against us, as fast as he was in this video," said Klich.
"The Swedes were doing sprints in training at the time and Jansson posted it online.
"I hope Pontus will play against us, because I haven't seen him for a long time and I'd love to face him."
With Sweden already through, Janne Andersson may decide to give players a rest and rotation could give Jansson his first minutes of the Euros, but having shut out both Spain and Slovakia and put together a mean defensive record since March, it's difficult to argue he should change his back line.
Klich acknowledges how difficult this evening's opponents will be to break down, but is confident Poland will find a way.
"We know that the Swedes conceded just one goal in the last seven games and are very well organized defensively," he said.
"However, if we play fast ball, we will concentrate on what we have to do, we are able to score at least one goal for them. I think that Robert Lewandowski himself would like to score two goals. We have a plan for this game, first of all we have to not concede at the back and we will definitely score something. We will fight."
Klich will be key to the fight, using his pressing ability to put Sweden under pressure and his creativity in the final third to try and unlock a stubborn defence.
He received a vote of confidence from boss Paulo Sousa after the pre-tournament friendly against Russia, although the Portuguese did say he expected more from the Leeds man.
Tonight would be the perfect time to deliver what his manager wants, when his country needs it most.
"I'm not 18 anymore and I know how it all works in football," said Klich.
"For the first time during the term of office of the new coach, I played in the match against Russia and in my opinion it was positive. I know the coach said after this game that I can play even better and I totally agree with him. I know I can give the team even more."