Three-time champion Ding is into his fourth final after a 6-3 victory over Tom Ford at the Barbican in York.
Ding had dished out a 6-0 thrashing to Ronnie O'Sullivan in the quarter-finals as the world number one suffered a first whitewash in a Triple Crown event in his 30-year career.
He told the World Snooker Tour: "I missed a great chance to win 6-0. I picked the wrong choices with the colour balls and he started playing more relaxed. I took my eye off a little bit and maybe lost a little concentration.
"He didn't miss anything in the last few frames. I like to play here, since the first time I beat Steve Davis in 2005, I love this venue. I always feel good in the Barbican."
Ding is aiming to win the title he last won in 2019 and raced into a 5-0 lead and another whitewash looked on the cards.
But world number 32 Ford, who beat Joe Perry 6-4 in his quarter final, hit back to bring the score to 5-3 with breaks of 77, 64 and 64.
Another 64 break gave him the chance to make it 5-4 but Ding took the ninth frame 75-64 to reach the final.
Ding will face Allen after he produced a stirring comeback to defeat Lisowski 6-5 in Saturday's late match.
Lisowski had made four centuries in a row as he defeated Shaun Murphy in the last round, and two half-century runs helped him open up a 2-0 lead.
Allen edged the third frame before a break of 63 levelled the match heading into the mid-session interval.
After exchanging frames following the restart, Lisowski capitalised when Allen missed a long pot chance of a red along the top cushion to move 4-3 ahead and then closed out the next frame to move within sight of victory.
Allen, though, fought back with a 115 clearance to take the ninth frame and 74 in the next after being let back to the table to force a decider.
Both men spurned chances to close out the match, with Allen losing position after a break of 36, before Lisowski made 57.
Allen then left the yellow over the middle, but Lisowski missed the green which proved costly as the Northern Irishman cleared up to complete another remarkable turnaround.
"I have no idea (how I won), that was awful," Allen told BBC Sport. "I just got in there and stayed mentally really strong, but I didn't really have any part of my game tonight.
"It was just a struggle from the start and I don't know why I'm sitting here the winner. Jack was much the better player. Just maybe my experience told, but I will need to improve tomorrow."