The jockey suggested to trainer Mark Johnston and his team that Nyaleti should be running over further after she won the six-furlong Princess Margaret Stakes at Ascot in July.
However, they stuck to that distance for the Prix Morny, but it proved too short as she was unable to get in a blow when sixth to Unfortunately.
One possibility was to test the water over seven furlongs in a race like the Rockfel Stakes at Newmarket, but the lure of this Group Two over a mile proved too strong.
"There's obviously a slight change in direction, going up in trip," said Johnston's son and assistant, Charlie.The daughter of 10-furlong Grade One winner Arch is set for step up in trip at Doncaster on Thursday (PA)
"Ryan did say after the Princess Margaret he thought this is the direction we should be going in, but we decided to punt, take a chance and go for the Prix Morny.
"We knew after two furlongs that the writing was on the wall. She just got outpaced and was struggling from a very early stage.
"Straight after the Morny, we decided we were going to go up in trip. The original plan was probably to go for the Rockfel and increase the trip in gradual steps.
"We thought we'd make the entry here and saw she was top-rated by 9lb on Timeform, so we thought it was too good an opportunity to miss. She should go very well."
Karl Burke is looking forward to Laurens tackling the mile after her debut success over seven furlongs on this course was followed by an excellent run to finish second to the highly-regarded Polydream in the Prix du Calvados at Deauville.
"She's a lovely filly and has got a big future ahead of her, I hope," said Burke.
"She's come out of the race in France really well. She was beaten by a potentially good filly in Polydream.
"The step up in trip will help her, although I wouldn't say she'd want any further than that at this stage on soft ground.
"I'd have preferred the ground just on the easy side of good, but she's in great heart.
"We go there with a good chance, I think."
She Believes gets the opportunity at Group level after she spreadeagled the opposition by six lengths in a nursery at Goodwood.
Trainer Sylvester Kirk said: "It's a huge step up for her, but she's in good form. She should like the ground and the step up to a mile.
"The quality of the race was questionable last time but she won very well and enjoyed the step up to seven. It's a tough ask but trip and conditions should suit."