The Bayern Munich star broke the Bundesliga all-time scoring record this season after he bagged 41 goals.
His national team produced an average performance in the friendlies in the build-up to the tournament as they drew 1-1 against Russia and 2-2 against Iceland.
The match is arguably the easiest in the group for both Poland and Slovakia as they will also play Spain and Sweden.
Here is everything you need to know about the match.
What time is the match?
The game will kick-off 5pm on Monday, June 14.
Where can I watch?
The match will be shown on ITV and coverage will start at 4.15pm. There will be a live stream via the ITV Hub.
For Poland, they are without Krzysztof Piątek and Arkadiusz Milik through injury.
And for Slovakia, Marek Hamšík’s fitness is questionable due to injury but he is set to feature.
Poland: Szczęsny; Piątkowski, Glik, Bednarek, Bereszyński; Krychowiak, Klich, Zieliński, Puchacz; Jóźwiak, Lewandowski
Slovakia: Dúbravka; Pekarík, Šatka, Škriniar, Hubočan; Kucka, Hromada; Haraslín, Hamšík, Mak; Duda
Poland – 3/4
Draw – 21/10
Slovakia – 9/2
If Lewandowski is on form Poland should bag the win over Slovakia to kickstart their campaign perfectly. The score won’t be high but Poland will happily take the victory. Poland 2-0 Slovakia.