The fourth-seeded Indian won 21-14 14-21 21-17 in a 45-minute battle against giant-killer Cheng, who had created quite a flutter by upstaging top seed Shixian Wang and seventh seed Xin Liu earlier in the tournament.
Saina had to dig deep in her armoury and rely on her power-packed smashes to outpace Cheng, who is known for her fast movement on court.
"I have seen her play in many tournaments. She is a very talented and hard working player. She is very dynamic and moves very fast on court. So it is important to have full force in the smashes or else she can retrieve from anywhere. It is a good win," Saina told PTI.
It was a sweet revenge for Saina who had lost narrowly to Cheng in the pre-quarterfinals of the Singapore Open in her last tournament.
"I had lost closely to her, that too was my own fault as I had given two points. I was upset after the match but I am happy I could beat her today. She played well but I was pumped up to do well," she said.