Sam Stosur admits Bernard Tomic would likely be collecting the most prestigious annual award in Australian tennis on Monday night if the rules hadn’t changed.

Instead, she says, the competition for the John Newcombe Medal is so close she can’t call a winner.

Former US Open champion Stosur, rising star Thanasi Kokkinakis, late-blooming Sam Groth, wheelchair quad world No.1 Dylan Alcott and doubles specialists Casey Dellacqua and John Peers are in the running for the award to be presented at a gala function in Melbourne.

Notably absent from the list are Australia’s top-ranked player Tomic and last year’s winner Nick Kyrgios are notable omissions.

Their omission comes from a tweak to the award’s criteria; from best performed to “most outstanding elite tennis player and ambassador for the sport”.

In other words it’s now an award for best performed and best behaved – and both Tomic and Kyrgios attracted unwelcome headlines through controversy in 2015.

With such varying records among the six nominees, Stosur, 31, said it was hard to say what what the judges would value the highest.

“I’ve won two tournaments, Thanasi’s really come up well for his age,” she said.

“Groth had a breakout year even though he’s a bit older and John and Casey have both made doubles grand slam finals a couple of times.”

“It’s all very diverse and capturing everything you can do in tennis.”

Tomic, 23, misses out despite ending the year as world No.18 – becoming the first Australian to finish a season in the top 20 since Lleyton Hewitt in 2005.

Stosur said Tomic, 23, would have been favourite if recognised.

“If everything else was good for him you’d think he would have been nominated and probably would have won,” she said.

A three-time winner herself, Stosur said she was “not overly confident” of making it a fourth, despite winning two titles in 2015.

The wildcard is Alcott, the first disabled athlete to be nominated for the award.

Alcott was a 2008 Paralympic gold medallist in wheelchair basketball before returning to his junior sport of wheelchair tennis.

In a sensational year, he claimed the Australian and US Opens on his way to becoming the wheelchair quad world No.1.

Alcott, 24, would be a popular winner after completing a 24-hour tennis challenge to raise money for charity in December last year.

The Newcombe Medal ceremony takes place as part of the Australian Tennis Awards at Crown Palladium on Monday night.