The decision to supplement The Highway Rat for the five furlong Group 3 Al Basti Pat Smullen Mercury Stakes in Dundalk reaped a good dividend when he brought up the fourth success of his career.

Ronan Whelan 's mount broke swiftly to lead but was headed by Strong Johnson after a furlong.

He remained in the van and took a narrow lead from that rival in the final quarter of a mile.

He came under the whip in the final furlong and surged home to close the race out by a length and a quarter. He was backed in from 9/2 to 18/5.

Charles Hills' raider May Sonic (7/1) put in late work for second at 7/1. He was two and a quarter lengths in front of Strong Johnson at 66/1.

Trainer Andy Oliver said: “That was just brilliant by Ronan. I said to him ‘just keep it simple, you know the horse now’ and he had no trouble in running — everything went smoothly.

“It’s particularly poignant as Pat was a great friend to all of us.

“He’s only a three-year-old and sprinters tend to improve. He’s thriving so well at the moment and is a horse to look forward to.

“We still have to make our mind up whether we travel over the winter but he is certainly a horse we’ll look forward to next year.

“He hit the line hard so I know he’ll get further. We have plenty of options with him now.

“I actually missed the entry for this race as we were very busy that week and we had to supplement which was a hiccup on my behalf.”

The Highway Rat is now four from nine with all his victories coming on the Polytrack at Dundalk. He is owned by the trainer's wife Saffron and named after their son's favourite book.

Additional reporting by Alan Magee