The summer signing from Vitesse Arnhem played the full 90 minutes at West Ham in the FA Cup on Saturday after Sir Alex Ferguson rested first-choice left-back Patrice Evra.
Büttner has also appeared once in the Barclays Premier League, scoring in the home win against Wigan, and featured in three European fixtures and two Capital One Cup ties.
After being bought as cover for Evra, the defender has already admitted he is pleased with his first months in Manchester.
"Alexander has made a great start," van Nistelrooy told ManUtd.com recently. "He needs a bit more time as he's definitely somebody for the future.
"He's been getting games in the Champions League. For him, it's a dream come true. He's got the ability and needs to learn to obtain more experience and he's definitely somebody to look out for."