One day after advancing beyond the semi-finals for the first time in his career, the 21-year-old Gulbis had a surprisingly easy time with his second seed Croatian opponent winning the match in one hour 20 minutes.
"Everything that I do now is the first time for my country," Gulbis told reporters. "I hope it's positive. They see that a guy from Latvia also can make it and win."
Gulbis won all eight of his service games and pressured Karlovic's serve.
After fending off a break point in the first set where he trailed 2-1, Gulbis took control of the match by breaking Karlovic to go up 3-2 and then win the next four games to close out the set.
Gulbis broke Karlovic again early in the second set and coasted to the triumph.
The big-serving Karlovic was celebrating his 31st birthday but had little to be happy about. While registering 14 aces he also made five double faults to open the door for the red-hot Gulbis who did not drop a set in the entire tournament.
It took Gulbis 65 tournaments to reach his second career ATP semi-finals, last week in Memphis, before he broke through this week.
"This year is going to be his breakthrough," said Karlovic.
"Everything that he hit was in. He was very cool, calm. Nothing could impress him."
(Reporting by Jahmal Corner in Los Angeles; Editing by Greg Stutchbury)