Moya is tied with world No. 1 Lleyton Hewitt and Andre Agassi with four tournament wins apiece. A victory here would allow Moya to move past Tim Henman into fifth place in the ATP Champions race, which determines the eight participants of the season-ending Tennis Masters Cup in Shanghai.
"I would love to win here but I'm still two matches away," he said. "It would be my first title indoors."
Moya needed to defeat a determined Blake, who was aiming for his third win over a top 10 player this year.
"I think I played a great match," Moya said. "It was a tough battle, we both had our chances. I expected it to be a tough match. I didn't feel in control of the match until the beginning of the third set. He's a very good player and he is going to be even better in the future.
"I kind of let it slip away," Blake said. "I played pretty well in the first two sets. It came down to a few points in the tiebreak. He hit a few great forehands past me. In the third set, he just rolled on. We play very similar, which is fun to play but it can also be very frustrating."
In Saturday's semifinals, Moya will face sixth seed Roger Federer of Switzerland, who rolled past Bohdan Ulihrach of the Czech Republic, 6-3, 6-3.
Federer, who won his only previous matchup against Moya more than three years ago, has not dropped a set this week as he seeks his third title of the season.
Fifth seed Jiri Novak ended the run of local favorite Jurgen Melzer, who ousted top seed Tommy Haas on Thursday, dispatching the Austrian, 6-4, 6-2.
"You can't play your best tennis every day. I couldn't reach yesterday's standard," Melzer said. "I had a lot of respect for (Novak) today, he's a very good player. I'm disappointed with the loss but tomorrow the joy of the success I had this week will dominate."
The Czech advanced to his seventh semifinal of the season.
The Romanian has yet to drop a set this week.