Henman, a quarter-finalist in New Haven, has also climbed one spot to No 20 but his points total of 1,616 is only 65 better than Rusedski, who has 1,551.
It means that if Rusedski does well in Boston this week he could regain the British No 1 spot which he lost to Henman on 29 April 1996.
Despite the two Britons' progress neither is likely to be seeded at the US Open which starts next Monday as all the world's top 20 have entered.
Monica Seles clinched a third successive Canadian Open title when she defeated Anke Huber 6-2, 6-4 in the final in Toronto.
Seles broke her German opponent's serve twice to take the opening set. Huber, though, recovered from 3-1 down in the second set to lead 4-3. However she then lost her serve twice more as Seles completed her victory on Sunday in 75 minutes.
For the 23-year-old Seles it was a second consecutive victory following her win in Los Angeles last week and suggests she is finding her old consistency as well as giving herself excellent preparation for the US Open.
"This is my favourite tournament, that's for sure," the world No 3 said. "I'm very glad that I did decide to come back and defend my title and I will come back next year too to try to keep the streak going. I wish I had a grand slam tournament here."
Huber, who has yet to beat Seles in eight meetings, admitted that once again Seles had proved too strong.
Yevgeny Kafelnikov won his second title of 1997 and rose to third in the ATP rankings by beating the eighth seed, Pat Rafter, 7-6, 6-4 in the International final in New Haven, Connecticut.
The top seeded Russian won pounds 100,000 while Rafter, who has lost all four of his ATP finals this year, settled for a consolation cheque of pounds 50,000 and the knowledge that his run lifted him to a career high of 14th in the world as well as becoming the highest-ranked Australian, passing Mark Philippoussis.
n Bjorn Borg won his second Mentadent Over-35 Champions tournament by beating the third-seeded Andres Gomez 6-3, 7-5 in the final in Mashpee, Massachusetts. Borg made only 11 unforced errors compared to Gomez's 46.Reuse content