“I knew from the beginning here it was going to be important to adapt right from the first game,” Lewandowski said. “People ask about the goals, but it’s important to be in the right position, to help my team because my teammates have helped me a lot on and off the pitch.”
Lewandowski said the goals were a gift to his wife, who was at the Camp Nou celebrating her birthday.
“The fact that she was in the stadium on her birthday means a lot,” he said. “Something amazing for me.”
Barcelona coach Xavi Hernández said he was running out of words to praise his new striker.
“Robert is relentless,” Hernández said. “He is humble and is always working hard. I don’t have enough compliments for him. He scored three goals today, but it wasn’t only that. It’s about how he helps the team, about his presence. What a fantastic signing.”
Frank Kessié, another Barcelona signing, and Ferran Torres also scored for the hosts in the Group C match at the Camp Nou.
Lewandowski’s former club, Bayern, won 2-0 at Inter Milan in the other group match.
Barcelona’s victory ended a 34-unbeaten streak in competitive games for Plzen. The Czech Republic club had won 10 of its first 12 matches this season. It entered Wednesday’s game with 29 wins, five draws.
Barcelona spent big to revamp its squad despite struggling financially in recent years. It finished behind Real Madrid in the Spanish league and was eliminated in the group stage of the Champions League last season, its first without Argentina great Lionel Messi.
The new signings have clicked early on and Barcelona has outscored opponents 16-2 to start the season.
Kessié, making his Champions League debut, opened the scoring with a header off a corner kick for his first goal for the Catalan club. Jules Koundé, another Barcelona signing in the offseason, redirected the ball toward Kessié with another header inside the area.
Lewandowski added to the lead in the 34th with a well-placed shot into the far corner from inside the area. He scored again in first-half stoppage time with a header after a nice cross by Ousmane Dembélé and with a low shot from outside the area in the 67th.
Lewandowski, signed from Bayern for nearly 50 million euros ($50 million), had already scored five goals in four Spanish league matches this season.
“Lewandowski showed his class tonight,” Plzen coach Michal Bilek said. “His finishing is phenomenal and he perfectly chooses the right position in the box. He is rightly considered one of the best forwards in the world.”
Plzen had pulled one closer in the 44th with a header by Jan Sykora after a defensive lapse by the Barcelona defense.
Torres scored the fifth goal for the hosts with a nice volley from close range in the 71st.
A penalty kick called in favor of Plzen in the 23rd was reversed after video review showed a foul by the attacker in the buildup.
“We expected such a hard match,” Bilek said. “The boys did what they could, but it was not enough. Barcelona showed tremendous quality in all aspects of the game.”
Barcelona got the easy win despite Hernández rotating his squad and making six changes to the team that defeated Sevilla 3-0 in the Spanish league at the weekend, with Kessié and Ansu Fati among those coming in and veteran captain Sergio Busquets and newly signed Raphinha being left on the bench.
Pablo Torre made his first-team debut by replacing Kessié in the 81st.
It was Plzen’s first Champions League game since 2018. It had won its last two games in the competition, as many as it did in its previous 16 matches.
Barcelona and Plzen had last played in 2011-12 in the group stage of the Champions League, with two Barcelona victories.
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