Full-back James Hook, wing Shane Williams and flanker Dan Lydiate are all expected to be available for Saturday's showdown.
Hook (shoulder) and Lydiate (ankle) both went off during Wales' punishing Pool D victory over Samoa in Hamilton 16 days ago and have not played since, while Williams missed runaway victories over Namibia and Fiji due to a thigh strain.
But they will take part in training on Wednesday, giving Wales coach Warren Gatland a full squad of 30 from which to select his starting line-up.
Lydiate's recovery has proved particularly impressive after he departed with ankle ligament damage just 10 minutes into the Samoa game.
As part of his initial bid to regain fitness, he woke at two-hourly intervals throughout the night to ice his ankle, and that approach now looks as though it has paid off.
Former Wales captain Ryan Jones took over from him in the Namibia and Fiji fixtures, while Leigh Halfpenny and then Lee Byrne deputised for Hook, with Halfpenny moving from full-back to wing against Namibia and Fiji.
"Dan, James and Shane have all been passed fit to train tomorrow," said Prav Mathema, the Welsh Rugby Union's national medical performance manager.
"Pending any adverse reaction, we expect them all to be available for selection against Ireland this weekend.
"Gethin Jenkins and Sam Warburton are also both fit for selection following calf cramp experienced during the end of the Fiji fixture."
Meanwhile Shaun Edwards has hailed the defensive effort against Fiji that helped them cruise into the World Cup quarter-finals.
"I was pleased with the lads because of their attitude, really," Wales assistant coach and defence specialist Edwards said.
"The lads were really disappointed that we didn't get a nil against Namibia.
"It's very unusual to get a zero nowadays in rugby. To get a zero you have to shoot out to a quite convincing first-half lead otherwise people go for penalties.
"Fiji battled on to the end and did their best, but our line held strong until the end of the game."
Edwards has urged Wales to seize the moment when they bid for a World Cup semi-final place at Ireland's expense.
Wales have not reached that stage since 1987. On that occasion they were beaten by hosts New Zealand before toppling Australia to claim a third-place finish.
"It is a moment in time you have to seize," Edwards added.
"Both teams will be giving 100% to try to make sure they are not the team who are packing their bags next Monday."
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