They have still seen plenty of each other.
After beating Xavier Malisse 6-3, 6-4 on Friday, the top-seeded Fish said he and Haas are "good friends" who live near each other in Los Angeles, often hanging out and practicing together.
"This is a guy that's trying to take my lunch away tomorrow, and I'm going to try to beat him any way I can," Fish said. "We'll remain friends off the court."
The fourth-seeded Haas routed Tobias Kamke 6-1, 6-2. Haas is 3-1 against Fish.
"He seems to be pretty close to back to 100 percent with his health and hitting the ball as well as I've seen him hit it in a long time," Fish said.
Fish reached the semifinals in the tournament for the first time in seven tries. Haas, also making his seventh appearance in the event, reached the semifinals in 2008, too.
Second-seeded Alexandr Dolgopolov will face No. 8 Sam Querrey in the other semifinal. Querrey, the winner last week in Los Angeles, beat No. 3 Kevin Anderson 6-4, 6-4, and Dolgopolov topped James Blake 7-6 (3), 6-4.
Top-seeded Anastasia Pavlyuchenkova advanced to the women's final with a 4-6, 7-5, 6-4 victory over No. 4 Vania King. Pavlyuchenkova will face Magdalena Rybarikova, a 6-3, 6-3 winner over third-seeded Sloane Stephens.
Pavlyuchenkova received treatment for a heat-related illness on the humid, 94-degree day.
"It was ridiculously hot out there," Pavlyuchenkova said. "I don't know seriously how people live here. It's unbelievable. I think they should consider changing the date of the tournament. ... I've been in Australia for six years, and I know what is hot, and I know it's the same for everyone. But today, it just hit me."