Fourth-seeded Nalbandian extended his unbeaten run in Basel to nine games as he got the better of U.S. Open holder Roddick for the first time, and stay on track for his first title of the season.
Third-seeded Coria, 21, secured a place in his seventh final of the year by beating Ivan Ljubicic 6-4 6-4 in the earlier match.
Nalbandian had lost to Roddick in their three previous encounters, including a sensational semi-final at Flushing Meadows when the American came back from two sets down to win.
But the Argentine, who is bidding to secure a spot at the season-ending Tennis Masters Cup in Houston, broke at 5-5 in both sets before serving out.
Nalbandian had broken in the opening game, only for Roddick to level the scores at 4-4. But the American was made to pay when he hit long at 5-5.
Both players held serve in the second set until Nalbandian claimed the match-winning break when Roddick hit wide to hand the Argentine a 6-5 lead.
Coria broke once in each set with the scores at 2-2 and big-serving Croat Ljubicic, who beat the world number five in Rome earlier this year,
CLAY-COURT SPECIALIST
"I'm very happy to be in the finals," said clay-court specialist Coria, playing in his first tournament since the U.S. Open.
"I didn't think that I would be in the final with the world's best indoor players here. I'm surprised. I had to play well, but Ljubicic didn't serve as well as he has," added the Argentine, after reaching his first indoor final.
Coria had failed to take his first break point in the opening set, but he grasped the second opportunity. He was then denied a second break when 4-2 up as Ljubicic held on.
The Argentine saved two break points when 3-2 up in the second set but from there offered his opponent no chance after twice holding serve to love.
Coria is chasing his fifth title of the season -- his four successes came in Hamburg, Stuttgart, Kitzbuehel and Sopot -- while he got to the finals in Monte Carlo and Buenos Aires.
It was a fourth semi-final defeat of the season for 24-year-old Ljubicic, who has played in only one final in his career, winning in Lyon in 2001.
Ljubicic had put home favourite and second seed Roger Federer out of the tournament in the second round on Thursday.