Coach Leon MacDonald said it was always in the back of coaches' minds to have players ready to cover for injuries, and they were mindful of that throughout the season.
"Losing our two premier locks in Sam Darry and Patrick wasn't ideal but we did get an opportunity to get minutes into other players and we're pretty confident there."
Tucker was forced to leave the field for an HIA early in the Highlanders game but passed it and returned to play, while Robinson, who played on the blindside flank, can cover at lock. Cameron Suafoa is another who can play at lock.
MacDonald was disappointed for Tuipulotu.
"It's brutally demoralizing. He missed last year and was excited about being in a Blues jersey this year. He was starting to hit his straps with his form and leadership and is a key player on our team. He's a huge loss to us.
"I was speaking to him after the game for 10 minutes, and he didn't say a thing, then 20 minutes later, in the sheds, he's walking around with a cast.
"He's not a man of a lot of words, and didn't even say he had a sore arm, but he obviously finished the game with it broken and didn't speak of it afterwards."
First five-eighths Beauden Barrett was fit to play and took part in training on Monday.
"If we really wanted to push him to the limit, we could have potentially put him out last weekend. Just the extra few days will make sure the wound has healed properly and didn't open up."
The Blues are not the only ones with injury concerns. The Waratahs will be without captain and halfback Jake Gordon (concussion, prop Harry Johnson-Holmes (syndesmosis) and have question marks hanging over, Jed Holloway (thigh), Langi Gleeson (back), Lalakai Foketi (ankle) and Izaia Perese (hip pointer).
Coach Darren Coleman said they would have their fingers crossed at training during the week.
"We'll take stock of who we've got. I think we've put too much work in for the last eight months to fly the white flag."
MacDonald said the quarterfinal would be different from when the sides met in the regular season. They rested several of their top players then, and they were aware of how good the Waratahs were when at full strength.
"The influence of Michael Hooper is massive, and he wasn't there that night, and his days in the blue jersey are limited, so he will be excited about finishing up well with them.
"We haven't reflected too much on last time we played them, probably more the momentum the 'Tahs have built in recent weeks and confidence in their game and we know how physical their pack is and we're making sure we're ready for that challenge."
The Waratahs were a proud side, and the quarterfinal would be an incentive for them to lift, and the Blue's job was to make that as difficult for them as possible, he said.
Coleman said when the sides last met, it was the first game at the ground for many of his sides, and they would be more familiar this time.
The Blues had a lot of skills, and Barrett would add another dimension to their effort. The Waratahs had learned from how the Highlanders had contained them in last Friday's game, and they would be doing their best to do the same.
QUARTERFINAL 1: Blues v Waratahs, Friday 9 June, 7.35pm, Eden Park. TICKETS.