Top Kiwi running prospect Sam Tanner completes sub-four minute mile, beating Nick Willis' old Kiwi record

Sam Tanner has beaten another of Nick Willis' records, becoming the youngest Kiwi runner ever to complete a sub-four minute mile at the Whanganui mile last night.

Tanner, 18, clocked a time of 3:58.41 to surpass his Olympic hero - the second record he's taken off Willis so far since he started running just two years ago.

Despite Tanner's superb run, he didn't actually win the race with Australian Rorey Hunter coming out on top with a time of 3:57.45.

But it was still a historic run for Tanner, who told 1 NEWS earlier this week he doesn't plan to slow down.

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Tanner has already broken Willis' U19 record for the 1500m. Source: 1 NEWS

"Ever since I started running I've kind of been like man I want to be an Olympian," he said.

"The more I race and the faster I get the closer my mind is to going yeah I can actually do this."

At the start of 2019, the teenage Tauranga native and national under 20 1500m champion took on his hero, Olympic silver medallist Nick Willis at the Cooks Classic, finishing just behind him.

However, he did manage to break Willis' under 19 record, pipping it by 0.68s with a time of 3:43.01.

The two also squared off at the 800m in the Capital Classic in January where Tanner came out on top.

Willis told 1 NEWS more of his records are likely under threat now.

"He's got a very light frame, he's a little guy who's going to be able to get around the track without taking a lot of wear and tear."