Instead, Halfpenny stayed at home to undergo rehabilitation on a quad injury he sustained prior to joining up with Lions on May 18.
That rehabilitation process has been a success so far, with the Cardiff Blues medical team hopeful that Halfpenny will join up with his Lions team-mates in the Republic.
"We're happy with the progress Leigh has made since returning to us," said Blues physiotherapist Tim Atter.
"He's running hard and is up to 80% and over the next two days we hope to get him back to full pace. We have worked mainly on strengthening and conditioning and Leigh has also done some light kicking.
"Leigh himself has been really positive and worked exceptionally hard - he is determined to get on the tour."