Dour stayer Mister Impatience needed every inch of the two miles to post an upset win in the Group Two Wellington Cup.

The proven long-distance performer was headed in the straight before he clawed his way back to claim a narrow decision at Trentham on Saturday.

Mister Impatience began his career in England with leading trainer Mark Johnston and won two races before he was purchased by clients of the Flemington-based Michael Moroney.

The six-year-old showed his staying ability with a 3000m victory at Ballarat and subsequently won the Listed Queensland Cup over 3200m at the Sunshine Coast last winter.

In the spring, Moroney sent Mister Impatience to his Matamata yard run by Chad Ormsby and the gelding finished fifth in the New Zealand Cup in November.

"It was a good run in the New Zealand Cup and he'd been working well leading up to this," Ormsby said.

"It's a big thrill, he's an honest horse and getting back out to the two miles again suited him."

Mister Impatience settled into the trail and challenged early in the run home only to be clearly headed by Pentathlon.

"He got a beautiful trip and just lobbed along," winning rider Sam Spratt said.

"He dug really deeply when I threw everything at him and he is a true stayer."

Mister Impatience rallied strongly along the fence in the closing 100m to earn a nose victory over Pentathlon, who looked set for the thick end of the stake when he took control 300m out.

Pacemaker Sampson fought on doggedly for third while the favourite Jimmy Mac was unable to make any impression in the straight and finished sixth.