Needing a big win to dislodge Riverside from third spot, the Knights fitted 62 overs in across the first session and a 90-minute block before stumps as persistent rain hammered Invermay Park.

Brodie Jarrad (2-17 off 11) had some early joy after opening the bowling with Graham Donaldson before Scott and opener Cobey Evans batted out the remainder of the first session.

Evans' defiant 11 off 112 came to an end immediately after the rain delay but Jonty Nicolson (15* off 76) proved equally steadfast, Mowbray reaching 3-134 at stumps with Scott on a career-high 90 not out.

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Mowbray coach James Storay said Scott's knock had been well-deserved following a remarkably consistent one-day campaign.

"He's had a bit of a lean couple of weeks with the bat, it's probably moreso the luck's been against him after Christmas - everything rather than a play and miss, he'd somehow find the edge," Storay said.

"But that's sort of what we're becoming accustomed to with Scotty, he digs in as captain and it was a captain's knock today."

Scott's three-hour knock featured 12 fours and narrowly trumped his previous best - an unbeaten 87 against Wynyard in 2018-19.

"He's a very laid-back individual ... there's little emotion from Scotty, but I'd imagine it would be a really good reward for effort coming through the ranks to where he is today," Storay said.

"He's just a bloke that trains hard, does a fair bit behind the scenes that no-one really knows about for his training and I'm really hoping that he comes out [Sunday], knuckles down and can get those 10 runs."

The Knights made two surprise selections for the final round, calling on veterans Nigel Page and coach Dean Hawkins for their first A-grade games in eight and 18 years respectively.

Hawkins bowled three maidens in an eight-over spell that yielded 0-16.

"We had someone lined up but they couldn't play Saturday-Sunday, so it was a great opportunity for Hawk to play," South captain Sean Harris said.

"It was nice for him to bowl and he bowled well."

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South will look to take the remaining seven wickets as quickly as possible on Sunday morning, with Mowbray able to bat until around lunchtime before an enforced declaration.

The remaining sessions promise to include some fireworks as the Knights play for their season.

"It's just a matter of trying to get stuck into them and hopefully knock them over quick enough so that we've got enough time to make their runs," Harris said.

"Mowbray were pretty resolute ... [Evans] was a bit of a thorn in our side and Luke Scott batted pretty well - we dropped him once when he'd already passed 50, but he batted well.

"They defended well and picked off things that were in their zone."

Jeremy Jackson (1-39) was South's other wicket-taker.

Just 16 overs were bowled at WESTBURY before stumps were called shortly after 3pm.

Launceston reached 2-51 with opener Cam Lynch (17) and James Lee (6) both unbeaten, with Jono Chapman and Nick Spencer Westbury's wicket-takers.

The Lions will be allowed about another 50 overs on Sunday before going into the field.

The rain put an end to Westbury's faint hopes of pinching an outright win and top spot on the ladder, but didn't overly concern Shamrocks skipper Dan Murfet.

"It was shaping up to a pretty tight day I would have thought, but there's still plenty of cricket ahead [on Sunday]," he said.

"I guess it's just a chance for us to prove ourselves against the guys that have been up the top all year and send a message to them that we're right there on their tails.

"We know we're going to get at least a session to bat, so we'll see how the day pans out."

Play resumes at 10.30am at both grounds.