Spieth had to work hard to win a barrier trial at Tatura on Tuesday morning, prompting David Hayes to shelve any thoughts of travelling to Royal Ascot with his recently acquired sprinter.
Damien Oliver travelled up to Tatura to trial several runners from the Lindsay Park stable including Spieth and Vega Magic, who is on target to resume in the Goodwood Handicap on May 19.
And while Spieth's winning margin over the lesser-performed Bold Approach was slight, both Hayes and Oliver are content with his progression.
"This is his third solid hit-out away from home and it was his best, I would say when we pick a race out for him he will be very competitive," Hayes said.
"I thought the trial was good but not probably sending me a message to go to Royal Ascot with him.
"We have got him down to run in the Goodwood, we are going to head that way I would say, just to me for a 1000m, as he has got more mature he will need the 1200m."
Oliver has been aboard Spieth in all three of his public gallops since joining the Lindsay Park team and feels he has improved with every hit-out.
"I was pleased with his trial, it is the third jumpout I've had on him and he is improving all the time as well, I felt that they quickened up really sharply over the last 400m of the trial," he said.
"I rode him out, he only does what he has to do, he is that kind of horse, he doesn't really do any more than you want to.
"He quickened up nicely and went past his opposition well I thought."
David Hayes, picture Quentinjlang.com
Vega Magic is being prepared to defend his Goodwood title and also won his heat at Tatura.
"It is probably not the ideal track for him, a tight-turning track, he is a big horse who probably prefers a bigger track but his condition is improving," Oliver said.
"That was his second jumpout and he may have one more before the Goodwood, he is a horse that races up on the pace so he needs to be nice and forward for a race like that but he is progressing really well.
"You can see visually his fitness has improved and I'm happy with the way he is going."
Lindsay Park also trialled Caulfield Cup winner Boom Time at Tatura and he is being prepared to resume on May 5.
"Considering it was a half mile, he got warm the last 200m, with a little shake up from Cory Parish he was impressive through the line so he is on target to probably to kick off in a 1400m at Flemington," Hayes said.
"We are running in the R.A. Lee and then bring him back to the Caulfield Cup next year."