LENOX >> Conductor Christoph von Dohnányi, who was scheduled to conduct the Boston Symphony Orchestra concert tonight and a portion of the Tanglewood Music Center Orchestra concert on Monday but has withdrawn from these performances due to complications following recent cataract surgery. BSO Assistant Conductor Ken-David Masur will replace Maestro von Dohnányi for both concerts. The programs remain the same.

Maestro von Dohnányi is expected to return to Tanglewood to lead the BSO in the orchestra's traditional season-ending performance of Beethoven's Symphony No. 9 on Aug. 28.

Masur began his appointment as assistant conductor of the Boston Symphony Orchestra in September 2014, and led the BSO in subscription concerts at Symphony Hall in November 2015.

In addition to leading BSO subscription concerts, Masur continues in his post as principal guest conductor of the Munich Symphony.

In 2011 he was the recipient of the Seiji Ozawa Conducting Fellowship at Tanglewood, where he returned by invitation as a Conducting Fellow in 2012.