There will be few more anxious trainers at Rosehill on Saturday than Ron Quinton as he prepares for the return of richly bred filly De An Andretti.

A full sister to the ill-fated Libertini, De An Andretti has been off the scene since she contested the Furious Stakes in September after contracting a virus that almost derailed her career.

While most similar illnesses are swiftly treated and cured, the virus contracted by De An Andretti was not straightforward.

Not only did the filly get extremely sick, but veterinarians had to experiment with several different antibiotics before finding one that worked.

“It was pretty bad. She was in hospital and it was a very severe virus,” Quinton said.

“We have had to be very vigilant with her. The vets caring for her, a girl at Agnes Banks called Laura, my vet Gary Bates and also a bloke called Peter Nestor, between the three of them they have done a marvellous job with her rehabilitation.”

De An Andretti will finally make her race day return at Rosehill on Saturday where she is an acceptor for the Ned Australian Whisky Handicap (1300m) and second emergency for the Midway Handicap (1200m).

Quinton is leaning towards starting her in the former, but that is as far ahead as he dares to think.

Given the ordeal the three-year-old has been through, the trainer admits he needs to see how she performs under race pressure before he can properly assess her and plan for the future.

“She is a quality animal. She has got very nice, natural ability and has always shown that from day one,” Quinton said.

“If she was a normal horse, you’d have to be very happy with her but you’re not going to know until the acid (race day pressure) is put on. That’s the big test.

“Naturally, the cream on the cake would be if she won, but hopefully she can run well and she can come through the race OK.”