Easterby has only been in New Zealand for less than a fortnight, answering the call to replace Dallaglio, who suffered serious ankle damage during the opening tour victory over Bay of Plenty.
But he won unstinting praise from Lions coach Andy Robinson following his midweek display against Wellington, and Lewis Moody's knee injury means that he now starts for the second time in four days.
"It has been about getting used to calls and new systems, and taking my Ireland cap off and putting my Lions hat on," said Easterby.
"It was a huge loss to the squad that Lawrence left. I came out here to replace him, but I certainly don't intend to replace him because no-one probably could - he's such a fantastic player and a fantastic guy.
"It would be very difficult to say I have come out here to fill his boots, because I haven't, but I enjoyed the experience on Wednesday night, and this will be no different. Hopefully, we can do the same as we did against Wellington."
Easterby is among several players in action with serious designs on the Lions 22 to face New Zealand in Christchurch next week.
"I don't think for one minute the Test side has been picked yet, so it has given those of us who are playing tomorrow a huge opportunity to show what we can do and push for that Test squad place," he added.
"I am delighted to have another chance. It meant so much to pull on the jersey on Wednesday, and I consider myself fortunate that I've got another opportunity within a very short space of time."