Montgomerie, a seven-time winner of the European money title, began the year ranked 14th in the world. He has won twice worldwide in the last two weeks, having shared the trophy at the Volvo Masters Andalucia with Bernhard Langer last week.
Tiger Woods has remained atop the rankings for 170 straight weeks. Woods, who has been ranked first for 240 weeks, has 94 weeks to go to reach Greg Norman's record.
Phil Mickelson, Ernie Els and Retief Goosen held their positions from last week. They were followed by Sergio Garcia, who moved up to fifth while David Toms dropped one space to sixth.
Vijay Singh, Padraig Harrington and Davis Love III stayed put, followed by Montgomerie.
Jim Furyk fell out of the top 10 to come in 11th this week. Nick Price held his 12th place ranking from last week, while Chris DiMarco and Angel Cabrera remained 13th and 14th, respectively.
Langer climbed two spots to 15th followed by Michael Campbell. Bob Estes jumped two places to No. 17 while Justin Leonard fell three rungs to No. 18 this week.
Scott Hoch moved up one position to 19th and Robert Allenby dropped two spaces to round out the top 20.