The world number 64 edged ahead three times during a cagey encounter before securing the final frame to book his place in the last eight at the Waterfront Hall.

Donaldson won the opening frame in a tight start, but Brown levelled before the Scot won the next two frames to move to within one of victory.

Brown responded again in the fifth to keep the contest alive, but Donaldson held his nerve to secure his first ranking quarter-final since the 2020 Northern Ireland Open.

"I get more enjoyment out of the playing aspect of the game, so it wasn't totally enjoyable tonight," Donaldson told BBC Sport NI.

"I got myself through to the next round and that is all really that matters but, obviously, playing Jordan is hard and then the table was really, really tough as the pockets were so tight.

"This combined with the fact that I'm not overly confident right now. I'm OK in patches but just all that made for a tough evening."

Elsewhere, Jak Jones held off a late fightback from Daniel Wells to progress with a 4-2 win.

Three-time world champion Mark Williams produced a commanding display to beat Martin O'Donnell 4-0, compiling breaks of 58 and 127 to reach the last eight.

David Gilbert also advanced with a win over Kai Wai Cheung, who had beaten Ronnie O'Sullivan in the first round.

In Thursday's earlier session, Kyren Wilson won a final-frame decider against Junxu Pang as he continues his quest for his first ranking win since his Players Championship win over Judd Trump in March 2025.

From 13:00 BST

Anthony McGill v Kyren Wilson

Sam Craigie v Elliot Slessor

David Gilbert v Mark Williams

Jak Jones v Scott Donaldson