The defending-champion advanced after a 6-3, 6-3 win.
The Croat is looking to duplicate his 2014 championship run
The Wimbledon finalist advanced past the Canadian 4-6 6-3 6-4 4-6 6-4
The 2016 US Open champion advanced 6-2, 5-7, 6-4
The 2009 US Open Champion is looking to make a return this year
The Latvian has reached the quarterfinals in New York the last two years.
The American will look to take his momentum into the US Open next week.
Competitors are tuning up in Vermont, for the final slam of the season.
The American advanced to the semifinals of the Stowe Mountain Lodge Classic.