Murphy will return from a three-week hamstring injury while Welsh is available after serving a one-match suspension.
However, defender Tom Williams remains a few weeks away as he overcomes a plantar fascia injury.
"At this stage Murphy and Welsh will play and we'll take a 23rd [player], but we're pretty confident they'll be right," coach Rodney Eade said from Whitten Oval on Wednesday.
Williams will make his way back via the VFL but won’t play until at least next week due to Williamstown having a bye this weekend.
Eade said the defender was still experiencing pain after snapping the plantar fascia in his foot prior to the round 10 match against the Sydney Swans.
"He might have actually tweaked the joint and there was a little bit of blood and swelling around it and there's still a little bit of pain at the moment.
"He's improved but he's still a couple of weeks away."
The Bulldogs will prepare for Port Adelaide's best side and form, despite the fact that injuries and inconsistency had dominated the Power's season so far.
"They've got a couple of injury problems, which hurts any team. But they've still got some quality players in their squad and they've been able to beat the likes of Hawthorn," Eade said of his opposition.
"Going up to Darwin, they'll enjoy that as well. We think it's a classic eight-point game for teams that are fighting for a top four spot."
Last year, the Bulldogs won just three more home-and-away season games after their Top End experience, and just two in 2007 before they missed the finals altogether.
Eade said he was confident the side would not suffer a similar fate this season.
"We've had a really good pre-season," he said.
"Adam Cooney is starting to hit his straps, he's getting a bit better each week so you'd think his second half of the season would be on the up.
"Murphy has had a bit of interruption but you'd like to think he's going to get better. Williams is the same.
"Last year we had our top four spot sewn up so I think there may have been a little bit of a drop in intensity at times.
"I don't think we played that badly. Everyone looks at the win-loss ratio and I didn't think we were playing super footy when we had 13 and a half [wins] out of 15, but unfortunately people just look at the win-loss and say, 'You're playing good or you're playing badly'.
"I'm certainly confident we won't drop away this year."
