Paul O'Donovan and Fintan McCarthy are fast becoming a seriously formidable double act.

Ireland's lightweight double sculls pair booked their ticket to the Tokyo Games on Thursday by making the A final of the World Championships in Linz and they'll hope this is the start of a beautiful relationship.

Paul and his brother Gary memorably took silver at the Rio Games but their paths have diverged for the moment, with the younger of the siblings teaming up with 22-year-old McCarthy after their boat performed best at Ireland trials at the start of the summer.

They took silver at the World Cup regatta in Rotterdam back in July and could go one better by winning gold on Saturday morning. 

Reflecting on their performance, both men said they were satisfied without getting too carried away.

"We weren't thinking so much about the Olympic qualification, just trying to get through each race and get to the final and thinking we'd try and win that if we got there," O'Donovan told RTÉ Sport.

"We knew if we could do that we'd also qualify for the Olympics as well. It's nice to have that done with early. If we'd ended up in the B final we'd have had to come in the first position in that to qualify. 

"We've been together now for a good bit of the summer and things were going well from the start. We'd a good training camp in Spain just before this too to put on the finishing touches."

McCarthy echoed those sentiments, airing his willingness to follow his partner's lead. 

"I was confident that Paul knew what he was doing so I was just trying to follow him!

"It was a good race. It was a good feeling crossing the line. Once the realisation hit after the race (that they'd made the Olympics), I had a nice minute or two of smiling to myself."

O'Donovan has a new look to go with his new crewmate - long hair and a bushy beard. McCarthy is sporting a few whiskers himself, but that's the one area he currently finds himself lagging behind.

"It's a bit of a pathetic attempt really," he laughed. "But I'm doing my best!"