Ullmark made 26 saves in Tuesday's 8-1 win over the Blues.
The veteran netminder took a shutout into the third period, but Dylan Holloway beat him on the power play with about 11 minutes left. Ullmark hasn't had quite the same success yet in Ottawa that he did in Boston, but through his first five appearances with the Senators, he has a 2-2-0 record with a 2.76 GAA and .904 save percentage.