The Glaswegian, forced to qualify for this year's tournament despite two final appearances in the last four years, edged out Mark Williams 5-4 in a high quality first-round contest.
"I was a little surprised I wasn't given a wild card considering my record here," the world No 10 said. "But with Jimmy White and Steve Davis around they're likely to get in the back door first."
Only the world's top eight ranked professionals receive automatic entry into the first major domestic event of the season. Three others are chosen by the sponsors and promoter Ian Doyle, while the fourth - McManus - had to win a six-player event to fill the last spot.
"I just looked at it as a chance to get in some match practice against quality opposition," said McManus, who beat Tony Drago 5-1 in Stirling earlier this month. "Had I lost I might not have been so happy."
McManus, beaten by Ebdon in the 1996 final, made a fine start but after leading Williams 2-0 he lost three in a row. He lost the third from 70- 0 up, the fourth after receiving a "kick" on the black when in prime position and the fifth when he went in-off after potting the third-last red. Undeterred, McManus fought back to level at 3-3 and then again at 4-4 before winning a 15-minute decider.