Matt Rowell, the No.1 draft pick who has played a key role in Gold Coast's recent impressive form, was widely considered a near-certainty to win this year's Rising Star award.

But it may not be a fait accompli based on the way Green grabbed the game by the scruff of the neck in the final stages of the Giants' two-point win over premiership favourites Collingwood on Friday night.

The second-gamer finished with 18 disposals, seven clearances and the first goal of his career.

It was in the frantic final three minutes, when the Giants desperately held onto their slender lead despite the best efforts of Collingwood's star-studded midfield, that Green did his best work.

"He certainly stood up in that last quarter," GWS ruckman Mumford told reporters.

"Joel Selwood would have been one from my early days (to show that much composure in his second game).

"That's something special. To be able to have the composure around the stoppage, know when to flick it out and when to hold it in."

Mumford joined the Cats in 2007 at the end of Selwood's all-conquering first season in the system, when he set the bar outrageously high by winning the Rising Star award and a premiership.

Geelong skipper Selwood will soon be gearing up for his 300th game, having won a stack of admirers and accolades over the past decade.

GWS coach Leon Cameron also heaped praise on Green, who re-signed with the club before making his debut in round one.

"He's just such a competitor. He stood up really well in those last couple of minutes," Cameron said.

"For a guy playing his second game, among some of the best midfielders in the competition, I just thought he made some really good decisions."

Mumford played his first game in nine months, having been recalled at the expense of Sam Jacobs as the Giants attempted to curb the influence of Magpies star Brodie Grundy.

The veteran, who turns 34 next week and came out of retirement for the 2019 season, is unsure how many games he will play in 2020.

"No idea. It's a real 'take it as it comes' season," Mumford said.

"I don't want to look too far ahead. Some weeks I might pull up shocking, other weeks I might pull up alright."

Australian Associated Press