Hege Riise praised Team GB's powers of recovery after they booked an Olympic quarter-final with Australia.
Caroline Weir's deflected leveller earned the Brits a 1-1 draw with Canada which was enough to top Group E.
Adriana Leon's second-half opener looked to have snatched victory for Canada before Weir, who had already hit the bar and post, struck late on in Kashima.
It meant Team GB won Group E with seven points and remained in Kashima to face Australia on Friday.
Riise said: "I believe strongly in this team, a great team always finds a way to come back and we did. Closer to the finish we started to get some momentum, luckily we were good enough to get the goal.
"It was an important goal (from Weir), we top the group, we're staying here and have a little bit more rest so we are happy.
"There are always things you want to improve on, we have played three games against three good opponents and have performed better and better. We haven't been together that long so we'll improve every game.
"Overall we looked strong and confident and that will be important going forward."
Riise rested three-goal Ellen White and made five changes, including starting Jill Scott and Rachel Daly, with Chelsea forward Fran Kirby on the bench for the first time after shaking off injury.
Needing to win to top the group, Canada had the first chance but Evelyne Viens dragged wide.
Georgia Stanway had a shot blocked before Team GB gained the upper hand and should have opened the scoring after 33 minutes.
Scott teed up Daly but the Houston Dash forward was denied by Ashley Lawrence's last-gasp block.
But Great Britain started the second half sloppily and Ellie Roebuck had already survived a scare after wasting possession before Canada took the lead 11 minutes after the break.
Lawrence burst down the left to find space and cut the ball back for Leon to fire in high from 12 yards.
White and Kim Little replaced Scott and Daly in response and Little almost provided Weir with an equaliser with 21 minutes left.
She fed Weir and her shot from an angle hit the underside of the bar and then the post before somehow bouncing away.
The introduction of White and Little reinvigorated Great Britain and Stanway then shot over.
With time running out Team GB finally levelled with five minutes left when Weir's 25-yard strike deflected off Nichelle Prince to wrongfoot Stephanie Labbe in the Canada goal.
Canada boss Beverly Priestman said: "On our day I definitely think we put out better performances the better the opposition. Our job is getting ready for the next game, one game at a time, but we absolutely believe we can get on that podium."
