If selected, the 35 year-old lock is set to become Wales all-time most capped player.
Llewellyn has been unable to train in recent days, but has recovered sufficiently to take to the park today.
Wales coach Mike Ruddock will name his squad to face the Pumas tomorrow, and should Llewellyn feature he will share the Wales cap record of 87 with Neil Jenkins.
Dragons lock Peter Sidoli is the other option Ruddock has in that position.
The Wales coach is expected to stick with the bulk of the side who beat the Barbarians 42-0 two weeks ago, for what will be a major physical challenge to be presented at Tucuman's notorious Estadium Atletico.
'[Wales captain] Colin Charvis told me he met one of the Argentinian props who is playing in France and was told that the Pumas are looking to beat us up,' said Ruddock.
'Our discipline will have to be excellent for us to match them up front and focus on getting the ball wide.
'If they go round hitting us and conceding penalties it could work to our advantage.
'I was in Tucuman with Swansea a few years ago and it is a very intimidating place, but we have to leave things to the referee and look to play rugby.
'We want to hurt people in the tackle, that's where you find out who the hard guys are.'