Imperatriz provided the star turn at Tuesday's Cambridge trials, getting the nod of approval from both Matamata trainer Mark Walker and jockey Opie Bosson.

The winner of the Gr.1 Levin Classic (1600m) and Gr.1 New Zealand Thoroughbred Breeders' Stakes (1600m) in the autumn, I Am Invincible filly Imperatriz raced handy in her 950m open catchweight heat on the Cambridge synthetic track before imposing her class in the closing stages.

Walker described Imperatriz as the stable's star triallist for the day, while Bosson was thrilled with her condition and performance.

"She felt great. She's back just as good as she was last time," said Bosson, himself returning to the trials for the first time since a winter holiday ahead of a raceday return at Te Rapa on Saturday week.

Walker was non-committal about Imperatriz's four-year-old programme, saying her races would be determined by suitable track conditions.

"She trialled up really nicely. She's pulled up well overnight and trotted up well this morning," Walker said.

"We'll see how she eats up towards the end of the week and firm up plans after that. 

"After she won the Group One at Te Rapa, she was out for about four weeks. She's quite a clean-winded type of mare. It just depends how the weather treats us over the next few weeks.

"It's always hard for horses when they go from three to four. Some cope with that rise better than others. Amarelinha is an example because at four she was disappointing after racing so well as a three-year-old.

"We'll just keep our feet on the ground and target some New Zealand races first and if her form warrants it, we'll consider a trip across the Tasman for her.

"Her programme will be dictated by the weather but the Tarzino is the logical target of course. She's coming along nicely."

The Gr.1 Tarzino Trophy (1400m) at Hastings on September 10 is two weeks after the now traditional lead-up of the Gr.2 Waikato Stud Foxbridge Plate (1200m) at Te Rapa on August 27.

Further trials were likely for several Te Akau runners from Cambridge, with the Te Rapa trial meeting on August 2 likely to attract a big stable contingent.

Quanttro Quinta, Synchronize and Marcus Aurelius ran well behind Imperatriz and were set to trial again, Walker said, as would Burgundy Rose, who won her 950m heat in good style.

On Burgundy Rose, Walker said: "She's stakes-placed so we'll just try and get a stakes win with her. That's the name of the game now.

"With them all, it's just getting the right opportunity for where they can kick off because it's rather wet at the moment."

Prise De Fer was third in the same heat, with Walker suggesting the Gr.1 Livamol Classic (2040m) at Hastings on October 15 as his spring target.

"He's a chance of running in the mile but his main aim is the Livamol and we'll try to give him his easiest path to getting there. A race like the (Gr.3 Jarden Stakes over 2000m) on Melbourne Cup day at Pukekohe would really suit him too."

Group One winner On The Bubbles finished second in his 950m trial, heading home four stablemates including Gr.1 Railway (1200m) winner Entriviere.

A tilt at the $A10 million Golden Eagle (1500m) at Rosehill on October 29 could beckon On The Bubbles if his spring form was strong.

"The group of owners are pretty keen on a trip to Aussie for the Golden Eagle but we'll just see how he comes up first. He'll either trial at Te Rapa on the second of August or else run over 1100m at Ruakaka on the sixth."

On Entriviere, Walker said: "I just don't think she let go on the track yesterday. She just pinned her ears back and said not for me. She's a funny girl like that. She was fine this morning so she'll trial at Te Rapa now."

Walker had 49 horses trial at Cambridge and gave a ringing endorsement for the Cambridge all-weather track.

"It's definitely got a place in New Zealand racing. I've just spent 11 years in Singapore and never had a horse trial on the grass the whole time," he said.

"People have just got to get their head around it, especially for winter and early spring trialling. We don't have enough turf tracks left to thrash them with trials.

"We just need to change our mindset in New Zealand. In the future, we'll be preparing them off the synthetic to go straight to the races. We did that for 11 years in Singapore and it does work."