Trainers Robbie Griffiths and Mathew de Kock have celebrated their biggest day on the racetrack together capturing a Group race double at Caulfield.

After the win of King Magnus in the Group 3 Kevin Heffernan Stakes (1400m) on the Saturday, the pair was back in the winner's circle 40 minutes later welcoming the win of Serasana in the Group 2 Sandown Guineas (1600m).

The pair teamed together in the spring of 2020 to form a training partnership, and while success at Stakes level had been achieved previously, nothing had come close to Saturday's success.

"This was the goal when we set out as a partnership," de Kock said.

"Thank you so much to everyone involved in us for the support, we really, really appreciate it.

"It's lovely to get a result like this because we've always thought really highly of this filly and John (Allen) just gave it an absolutely perfect ride.

"So, what a day to have a Group race double."

Specked at odds, Serasana ($13) rode the speed after crossing from a wide draw to score a 2-½ length win from the $2.80 favourite Arkansaw Kid with Vivy Air ($4.60) a length away third.

Griffiths and de Kock had the Group 1 Thousand Guineas (1600m) at Caulfield two weeks ago in mind for Serasana, but a set-back put an end to those plans.

"We always had the mile distance in the back of our mind, and we actually wanted to be ready for the fillies' Guineas," de Kock said.

"We had a little hiccup in the prep which put us on the back foot, so we just took our time with her and focused on this race.

"As you can see today, she's going to make a lovely miler when she's older because she's still immature."

De Kock was put at ease by Griffiths as to whether Serasana would handle the soft track that was downgraded further after King Magnus had won.

"I had to go to my pedigree guru Robbie Griffiths to ask him about Snitzel's in the wet, but he was pretty confident that they handle it," de Kock said.

"She was fit and well and there was no reason not to run today."