Montgomerie hasn't played since pulling out of the World Golf Championships-NEC Invitational in Seattle on Aug. 23 after playing 27 holes.
He waited until Monday to decide whether he could resume playing this week. Montgomerie is also in the field for next week's World Golf Championships-American Express Championship at Mount Juliet in Ireland.
The Ryder Cup is Sept. 27-29 at The Belfry in England.
Ryder Cup player Padraig Harrington also is scheduled to play in Germany. He has experienced neck and ankle problems this summer.