The 31-year-old left his boyhood club Bayern Munich to link up with Louis van Gaal at Old Trafford, and Gunners defender Mertesacker believes his national team-mate can become the player Red Devils have been craving in midfield.
In an interview with Die Welt, Mertesacker said the transfer of Schweinsteiger shows how much respect German football has in the world right now.
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He said: "He's the next example of how big the respect for Bundesliga and German football is by now. I think it's great that 'Basti' has taken this step. It takes some courage to just leave Munich and FC Bayern. He had a certain status there, and was at a club subscribing to the domestic title.
"He knows that a lot is expected of him as a world cup winner. It's incredibly important for him that he stays healthy. Should that be the case, he will implement everything Louis van Gaal expects from him.
"He can become the central player at Manchester United, who like to control the opponent and then breakthrough in the deciding moment."
UNITED NEED TIME TO GEL
Schweinsteiger arrived in England as a winner having claimed bundles of silverware at Bayern Munich. He will be hoping to continue his fine trophy haul following his move to Old Trafford.
United looked laboured on the opening day, but ground out a 1-0 win against Tottenham Hotspur, something sides have to do if they want to be in with a shout come the end of the season.
The Red Devils will take some time to reach their free flowing best, with so many new additions going straight into the starting line-up. However the signs of a strong side are there.
Memphis Depay showed signs of his flair and trickery, but will need time to adapt to a new position and league, Matteo Darmian looked assured and composed at both ends of the pitch while Morgan Schneiderlin offered physicality in the centre of the park.
If United can gel quickly they are sure to become a force to be reckoned with this season. That is a big if however, as their lack of clear goalscoring opportunities in the opening game pointed to a lack of chemistry.
United fans: Were you impressed with 'Basti' once he came on? Have your say below!