Wales' RBS 6 Nations championship winning hooker Hibbard spent 50 minutes playing alongside Corbisiero and then watched from the stands as Grant joined Rory Best in a new look Lions front row for the remainder of the game.
The two players flew in to Australia from their respective national team tours in South America and South Africa following tour ending injuries to Cian Healy and Gethin Jenkins. They joined England's Mako Vunipola as the loose head specialists in the squad fighting for a Test place.
"Fair play to the replacements - it shows great character to step onto the pitch almost as soon as you've got off the plane. They went alright and both did really well," said Hibbard.
"I'm gutted for the two players who have had to go home, but fair play to Alex and Ryan they came off the plane, onto the pitch and did the job."
Hibbard grabbed his first try for Lions in the 27th minute of the romp in Newcastle, but was still left with a feeling that the tourists should, and could, have bagged more points and tries in the game.
"The Country XV showed character out there and defended for their lives. There were some positives for us to take out of the game, but I'm sure Warren will add his view once we've all seen the video," said Hibbard.
"He is bound to be a little bit disappointed with the second half performance because there is so much more to come from us. There was a bit of frustration because you never like to let a few tries slip through lapses in concentration.
"We've got things to put right and there is a lot more to come from us. We're still trying to get more minutes with each other on the park in the build up to the Test series and get more wins.
"The confidence is there within the squad in the build up to the Tests. We won 64-0 with 10 tries against the Combined XV and we know there is still a hell of a lot more to come from us and I think we can push on from here.
"We've got four wins, scored countless tries, were tested against the Reds, who showed good pace but once again we put in an excellent performance against them, so we keep on building and pushing on with this squad. We are very confident."