"The risk in the near term is that it continues to defy consensus," he said.
But he added that ultimately the trade could be proved right. "Once we get nearer to the first Fed tightening there is scope for dollar-yen (to rise)."
The latest data showed currency speculators pared bets on the U.S. dollar in the weekended February 11.
Nevertheless, it was the 15th straight week in which speculators held net long positions in the greenback, reflecting a wider belief that the Fed will probably continue to wind back its extraordinary policy stimulus this year.
Volumes were thin in most currency pairs, with U.S. markets closed for Presidents Day and no major European data scheduled. Investors will keep an eye on a lecture by European Central Bank governing council member Ewald Nowotny later on Monday, after he earlier said there may be a case for waiting and seeing if it should change interest rates.
(Read more: Euro zone's surprise growth boosts recovery hopes)
The euro rose 0.2 percent against the yen to 139.67 yen, helped by data on Friday showing both Germany and France grew slightly faster than expected in the fourth quarter, pushing the euro zone's recovery up a gear.
Commodity currencies such as the Australian dollar were also in favor after Chinese lending data on Saturday suggested the world's second biggest economy may not be cooling as much as feared.
However, analysts warned that the data could be distorted by the Lunar New Year holidays in January. China is the biggest export market for Australia and New Zealand.
The Australian dollar hit a fresh one-month high of $0.9070, before ceding some ground to last stand at $0.9033.