Biggar overjoyed to prolong test career as he returns to Wales line-up
Biggar sat out Wales' last two games after sustaining a pectoral muscle injury in the 40-6 win over Australia last month, in the pool phase of the tournament in France.
His return for the knockout stages is a boost for Wales and obviously pleasing for him, who announced last month he was ending his international career after the World Cup.
"It was one I really didn't want to miss and I'm lucky and grateful to be sat here," he told a press conference on Friday.
"It would have been such a shame to end it that way.
"I'm alright. I just managed to get back last week, sitting on the bench. I thought it might be difficult but it's healed up well," he said of the injury.
Biggar's considerable experience could well prove key for the Welsh, aiming for a second successive World Cup semi-final after winning their pool with an unbeaten record. But he warned overcoming Argentina on Saturday would be no easy task.
"We've got to manage expectations. I think a lot of people think we can just turn up and win. That's not the case. We need to deliver a really good performance. We're playing a tough team who probably have more to come," he said.
Ending his test career, in which he has earned 111 caps, at the World Cup means some added motivation.
SPECIAL WEEK
"I don't want my last day as a Welsh player to be losing a quarter-final and I'm not thinking about this as potentially my last Wales game," he insisted.
Instead, Biggar has looked to savour the experience of what he called a "special week" as Wales have risen rapidly out of the doldrums from a miserable Six Nations campaign at the start of the year and a myriad of off-field controversies.
"We're not quite ready to go home. It's funny how time changes. If someone had said we'd win our pool and be in a strong position three or four months ago, you'd think they were talking madness," he added.
"These are the reasons you play rugby. It's been a really special week. The prize at the end of it is why we want to be involved."