Lewandowski had been linked with a move from Borussia Dortmund to Bayern for up to a year but the transfer was finally confirmed on Saturday with the Polish forward set to move to the Bavarian giants at the end of this season.
While Bayern are the leadinggoal-scorers in the Bundesliga this season, with the likes of Mario Mandzukic (10 goals), Thomas Muller (seven), Franck Ribery and Robben (both six) regularly finding the back of the net in the German league, Lewandowski is the equal-leading marksmen with 11 strikes to his name, alongside Hertha Berlin's Adrian Ramos.
Lewandowski has scored 91 goals in 165 competitive fixtures in his time at Dortmund and with that kind of scoring pedigree, Robben is convinced the 25-year-old striker will make a difference for Pep Guardiola's Bayern outfit.
"I think he's a great player and one of the best strikers in the world," Robben told Sport 1 in Germany.
"We're already pretty strong but he'll make our squad even stronger and that can only be a good thing."
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