Manager Ryan Giggs praised Wales' win in Azerbaijan as one of the best performances of his reign.
"Some of the quality of play was outstanding," Giggs said.
"Since the Azerbaijan game at home [in September], we've improved," the former Manchester United winger added.
"We've played some difficult teams, Slovakia, Croatia, but overall the performances have improved.
"We started to gain some sort of momentum, which isn't easy in international football. The lads came into camp really confident. The last few games, it doesn't matter whose come in, they've all contributed.
"Azerbaijan is not an easy place to come and the pressure, so it's up there with one of our best performances."
Giggs and his players faced a nervous wait on Saturday, flying back to Wales from Azerbaijan while Slovakia faced Croatia.
He had joked in the post-match news conference that he would ask the pilot to keep them updated on the score in Rijeka.
Robert Bozenik had given Slovakia the lead but second half goals from Nikola Vlasic, Bruno Petkovic and Ivan Perisic secured Croatia a 3-1 win and a place in next summer's finals.
Ramsey and Bale fitness boost
As well as the result and performance, it was also an excellent evening's work for Wales on the fitness front.
They were able to take Gareth Bale off after an hour, managing the Real Madrid forward's workload after a month out injured.
Giggs replaced him with Aaron Ramsey, making his first appearance of the qualifying campaign after a series of injuries.
Having carefully balanced the two players' workloads, Giggs now hopes to be able to start both Bale and Ramsey for Tuesday's pivotal fixture against Hungary.
"It was a difficult decision. I thought if both started, then at least one of them wouldn't be able to play on Tuesday," Giggs added.
"We've still got to assess it. It couldn't have gone any better regarding minutes - getting Gareth off pretty early and getting Aaron some minutes as well. When he came on he showed his quality, his composure.
"It's a quick turnaround. Gareth was blowing a little bit which you can expect, but hopefully I'll have the option to start both on Tuesday all being well."