Sea Eagles halfback Apisai Koroisau scored a try against Souths in Round 5.

Former Rabbitohs Dylan Walker and Api Koroisau were the unexpected halves combination for Manly on Thursday night and while each was deeply disappointed to have fallen short of grabbing a win against their old club have vowed to learn from the match.

The ex-Rabbitohs pair were two of their side's best in a comeback that fell just short, scoring a try apiece in the three-tries-to-two loss, doing admirably in trying to manage the game to a simple game plan despite limited experience in that task.

"There was extra incentive there being the old club but at the same time any game it'd hurt just as much not coming away with the two points but we've got another long week coming up here before the Warriors," Koroisau said after his man-of-the-match performance.

"I think it was a good game plan from Trent Barrett; he kept it very basic and me and Dylan just worked off that which turned out to work pretty well but unfortunately it didn't come off in the end."

Regular rake Koroisau's last game in cardinal and myrtle was the 2014 premiership win, starting at hooker for the suspended Issac Luke, and he spent 2015 at Penrith before following former Panthers assistant Trent Barrett to the northern beaches.

Walker stayed a season longer before being identified as a potential replacement for Kieran Foran in the Manly No.6 jersey.

Barrett wouldn't have banked on losing star half Daly Cherry-Evans and took a gamble on the makeshift pair, with reserve half Isaac John still struggling fitness-wise in his comeback from a hamstring injury.

The emotion showed by Walker after he scored his team's first try showed how much the game meant to him.

"It's pretty disappointing losing to your old club to be honest," Walker said, but praised the efforts of Koroisau coming into an unfamiliar position after a fortnight playing Intrust Super Premiership.

"I thought Api played really well, he was probably one of our stand out players, he came in and did the job really well. As a team effort it was really good but we didn't get the win so it was pretty disappointing," Walker said.

"The way he bounced back just shows you how much character the bloke's got, he's pretty strong willed and I thought he was our best player."

Between the two halves and fullback Brett Stewart there were some wobbly last-tackle options through a final 60 minutes of the match in which Manly were the better team overall but just unable to deliver the final blow, though no one was blaming the loss on the kicking game.

"We gave ourselves a lot of chances to win that game but we just didn't get across the line," Walker said.

"We'll look at it in video, there were a couple of repeat sets the boys got and we had plenty of chances to win but we didn't get over the line."

Added Koroisau: "I think it's our defence [that needs work], not really too much in attack but I think mainly our kicking game, I think we could be a lot better there at putting it into corners to hopefully help our defence out."

The Fiji international also admitted it was a huge change to his regular role after just six career games in the halves previously, all last year in an injury-hit Penrith side.

"It's a totally different game. It's definitely a lot more talking and a lot more dominance out there, you just have to keep your head and call the shots and hopefully I did that out there," he said.

"It was a bit of a challenge this week coming in and playing in the halves and I've got to give it to the boys, they made my job a lot easier and gave me the confidence to go out there and do a job and helpfully I did that.

"We had a real short week, one of those five-day turnarounds everyone's been talking about. We only had the captain's run to work on our combination there so I'm pretty happy with the way it came off, we just need to work on a few more things at the start of our game," he added.

Walker felt like he was improving week to week in his transition to a five-eighth after making his name as a centre.

"I like to think [I'm improving], the last couple of weeks I've been a lot better. There's a couple of things [against Souths] I wish I could take back but it's something I can look at in the video and help my game even more."

With coach Trent Barrett having all but guaranteed the pair will stay together in the halves until the return of Chery-Evans in around a month, and also promised the side three days away from footy before regrouping to prepare for the Warriors, Walker was just glad for a short respite after a gruelling fortnight.

"These next couple of days we really just have to look after our bodies, it's been tough the past couple of weeks so get out bodies right first, come to training on Monday and really rip in and the better we train the better our performance will be on the weekend. The Warriors are a tough outfit and we have to be up to the task," he said.