British and Irish Lions outmuscle Australia to win first Test 27-19
The tourists repeatedly laid siege to the Wallabies line for a 17-5 lead at the break before soaking up second-half pressure to bank the win with both sides scoring three tries.
A late Australia try in front of 52,229 fans at a sold-out Suncorp Stadium, many wearing Lions red, meant the scoreline flattered a ragged Wallabies side, with Andy Farrell's team never in serious trouble.
"We're delighted with the win, the game was a tough Test match," said Itoje.
"I thought we started well, first half we played a lot of good stuff. Then the second-half was a bit to and fro from both sides.
"There's stuff to work on and the coaches are going to have a hard look at that game and there's going to be some really good things that we can take out of it."
With Scottish fly-half Finn Russell pulling the strings in the backs and outstanding loose forwards Tom Curry and Tadhg Beirne dominating up front, the Lions showed why they were firm favourites.
But despite being behind for all of the match, the Wallabies refused to roll over and fears of a huge defeat never materialised.
"It's obviously disappointing, we came here wanting to win," said Australia captain Harry Wilson.
"I feel as if we probably didn't really get our game going like we would have liked, but our lines were good, and credit to them.
"They won a few big moments and that's something we want to do, and make sure we do next week."
The second clash in the three-Test series is in Melbourne next weekend.
The Lions got away to an almost perfect start, Beirne winning a penalty from the kick-off and Russell slotting an easy three points.
The Wallabies barely had the ball in the opening 10 minutes, the Lions dominating attacking possession to give the sea of red jerseys in the crowd plenty to cheer about.
The home side were made to pay when inside centre Sione Tuipulotu ran on to a beautiful long pass from Russell, which missed out four players, to cross unopposed next to the posts.
It gave the Lions a 10-0 lead in as many minutes and they dominated possession and territory over the opening half an hour so much that it was a surprise when Australia hit back.
Sheehan strikes
Wing Max Jorgensen came away with the ball after Jake Gordon hoisted a high kick inside the Lions 22 and beat Russell's despairing covering tackle to score in the corner.
Tom Lynagh missed the conversion, leaving the Lions 10-5 ahead eight minutes before the break.
The Lions went straight back on the attack and their intentions were clear when Itoje turned down two kickable penalties, opting to go for a try.
They missed out the first time but were rewarded moments later when Curry barged over, giving the Lions a 17-5 advantage at the break.
The Wallabies needed to start the second half well, but instead it was the Lions who struck first, hooker Dan Sheehan finishing off a Hugo Keenan break and crossing in the corner.
Russell's sideline conversion gave the visitors a commanding 24-5 advantage.
The Wallabies thought they had struck back after some sustained pressure when Joseph-Aukuso Suaalii barged over under a pile of Lions.
But referee Ben O'Keeffe reviewed video footage which showed Suaalii had not released the ball as he was dragged over the line by the defenders and the decision to award the try was reversed.
With the match slipping away, replacement flanker Carlo Tizzano burrowed over for Australia and Ben Donaldson's conversion made it 24-12 with 12 minutes remaining.
A penalty goal from Lions replacement fly-half Marcus Smith right in front gave them a safety net at 27-12.
Wallabies reserve scrum-half Tate McDermott scored a consolation try just before the siren, but it was too little too late.