Montgomerie, bidding to become the European No 1 for the fifth successive year, made this plain in Berlin yesterday after the pro-am at the Linde German Masters.
Montgomerie said: "I've a decision to make and I shall make it five days after the Volvo Masters which ends on November 2. I have my US Tour card and now it is up to me. Whatever I decide, one thing is certain. I shall not try to play on both tours. Ernie Els tried it this year but could not manage it."
Montgomerie certainly gave the impression that he is America-bound. "It was a big blow to the European Tour when Nick Faldo left," he said, "but the Tour survived and our Ryder Cup victory has certainly helped the Tour's prestige."
But Montgomerie implied he had no more worlds to conquer in Europe by saying: "If I do make it five in a row that will be the end of this."
The 34-year-old Scot is leading the Volvo Order of Merit by pounds 81,000 from Irishman Darren Clarke with only three counting tournaments to be played.
If he finishes top again he will have set a new European record, beating the previous best of four successive years which he holds jointly with Peter Oosterhuis, who had his four wins from 1971 to 1974 when the competition was not so fierce.