They had to recover from two penalty tries conceded by defensive scrums, one in each half, plus a lop-sided penalty count from referee Mike Fraser, but they did so with both panache and grit.
The five minutes or so before halftime featured an incredible defensive effort from the Blues, who stymied an attempted Waratahs lineout drive, won the resulting scrum, lost the ball, and then spent the next few phases tackling as if their lives depended on keeping the visitors out.
There were several highlights but the most memorable were the superb tackle by the excellent Kara Pryor on Bernard Foley under the posts and, even more significantly, Melani Nanai's tackle on Israel Folau to force a knock-on just before the halftime hooter sounded.
It allowed the Blues to take a 12-7 lead to the break, and they thoroughly deserved it. They had given up a penalty try from a scrum after 20 minutes, referee Fraser losing his patience with the front row, but they got one themselves via a collapsed lineout drive, which came following Patrick Tuipulotu's gallop down the left touchline for a deserved five-pointer.
Piers Francis's try, a response to the Waratahs' second penalty try, allowed the Blues to re-take the lead and he got to the line after beating five defenders, a score which highlighted why he won the franchise's rookie of the year award this week.
What followed was a give-and-take sequence of punch and counter punch, Folau scoring for the Waratahs following a rare sequence of sustained attack by the visitors, Nanai the beneficiary of an Ihaia West chip kick which hit a defender, Angus Ta'avao scoring against his former team, and then replacement midfielder George Moala strolling through a huge gap to put the game almost beyond doubt in the final minutes.
Moala, and prop Charlie Faumuina, were only given the go ahead to play on the day of the game due to respective elbow and knee problems, but both added impetus to a superb team performance.
Tuipulotu, Jerome Kaino, Pryor, Nanai and Francis were outstanding for the Blues, but they all were; it was a brilliant way for them to finish, and not such a great one for the Waratahs. Daryl Gibson's men got a bonus point all right, but it was a losing one.
Blues 34 (Penalty try, Patrick Tuipulotu, Piers Francis, Melani Nanai, George Moala tries; Piers Francis 3 cons, pen)
Waratahs 28 (Penalty tries 2, Israel Folau, Angus Ta'avao tries; Bernard Foley 4 cons)
Halftime: 12-7