Connections of two-year-old Fontiton have warned there is plenty of improvement to come after the talented filly maintained her place at the top of Blue Diamond betting with a narrow first-up win at Sandown.

Fontiton ($1.90) was forced to work hard to keep her unbeaten record in tact, getting home by a neck in Monday's Group Three Blue Diamond Preview for fillies over 1000m in her first start since winning impressively on debut in October.

The Robert Smerdon-trained filly remains the $4.40 favourite for next month's $1 million Group One Blue Diamond (1200m) ahead of the Mick Price-trained Secret Agenda, which did not run in the fillies' Preview.

Burnstone has moved to the third line at $8 after the colt's 3-1/2 length win on debut in Monday's colts and geldings division.

Fontiton recorded a winning time of 58.13 sec, shading Burnstone's time of 58.34 seconds.

Jockey Mark Zahra said Fontiton quickened nicely and loomed up to win easily after taking a sit behind the lead but felt the filly peaked on her run first-up.

He noted the filly had had a soft jumpout leading into the race and was at her most vulnerable on Monday.

Fontiton defeated Haybah ($21) with 1-3/4 lengths to debutante Pursuits ($26) which has firmed to $12 for the Blue Diamond.

"If she was really fit I reckon she would have put them away quite easily," Zahra said.

"The second horse (Haybah) has been in work a long time and had a lot of fitness up its sleeve. I reckon she had had enough 100-metres out, but she wasn't going to let the other horse beat her.

"She's got that good winning attitude."

While Fontiton clocked a quicker winning time than Redoute's Choice colt Burnstone, trainer Robbie Griffiths took heart out from the way Burnstone surged home along the inside from back in the field to win his division of the Previews.

"The leader (Top Me Up) finished second and when I look at the sectionals, my horse was nearly a second quicker than the others in the race," Griffiths said.

Fontiton is set to run in the Blue Diamond fillies Prelude on February 14 before the Blue Diamond two weeks later.