Czech seventh seed Rosol got the better of Taiwan's Yen-Hsun, edging the ninth seed 7-5 4-6 6-4 in the semi-final of the ATP World Tour event.
After almost surrendering a 5-2 advantage in the second set, Rosol broke Lu's serve to take a 5-4 lead in the deciding stanza and fended off three break points as he claimed the match in two hours and three minutes at Wake Forest University.
"I'm happy for this result and I hope it's not finished yet," said Rosol, who has reached the quarter-finals or better at his past five tournaments since losing to Rafael Nadal in the second round at Wimbledon.
"I was not down in the third set. I was the first one to break. You just have to (mentally) stay in the court.
"I have some work in front of me and I'm always trying to find the highest possible level."
Rosol, who sent down eight aces and claim a total of four break points, will now face unseeded Pole Janowicz in Saturday's showpiece clash in North Carolina.
Janowicz, who earned successive wins for the first time in 2014 this week, came from a set down to topple American hopeful Sam Querrey 4-6 7-5 6-4 in two hours and 18 minutes.
Despite losing the ace count 18-7, Janowicz won five breaks of serve and saved 16 of his own to set-up a fourth career meeting against Rosol.
Janowicz leads the head-to-head record 2-1, though only one of those matches have come on the ATP circuit, with the Pole winning that clash in Marseille last year.
The two previous meetings were on the Challenge Circuit in Prague (2011) and Germany (2009).