Brett Robinson and Sinead Diver have broken Australia's long-standing marathon records within hours of each other.

Robinson finally eclipsed the mark set by distance running legend Rob de Castella, which had stood since five years before he was born.

After Robinson made his breakthrough at the Fukuoka International Marathon in Japan, Diver broke the Australian women's record at Spain's Valencia Marathon.

The 45-year-old bettered Benita Willis's 2006 record of 2 hours, 22 minutes and 36 seconds by more than a minute, crossing the line in 2:21:34.

"Huge congrats Sinead Diver on your Aussie marathon record today!" Willis wrote on Instagram.

"Was an honour to hold it for so long. Couldn't have been broken by a better athlete/person. Amazing."

Diver broke her personal best by nearly 3 minutes after finishing 10th at the Tokyo Olympics. It came just a couple of hours after Robinson took down a marathon mark that had stood for 36 years.

Robinson, 31, finished fourth at Fukuoka in 2:07:31, breaking by 20 seconds de Castella's record that had stood since he won the 1986 Boston Marathon.

Robinson, a two-time Olympian, beat his personal best by 2 minutes and 21 seconds.

In October, he became only the sixth Australian to join the sub-2:10 club when he finished the London Marathon in 2:09:52.

"It's such a great feeling. I've gone for this record a few times now, and it's funny — I always talk about going for it before a race," Robinson said.

"But I didn't mention it to anyone this time around. I went about my own business and I finally got it. I knew I was capable of it.

"The current crop of Australian athletes are smashing records at the moment, and this was one of the last long-standing ones for us to tick off, so it means a lot to me to finally get this today."

Steve Moneghetti, whose 2:08:16 is now the third-best Australian time, paid tribute to Robinson.

"I also want to give credit to Deeks (de Castella) for holding the record for so long," Moneghetti said.