South Africa took an unassailable 3-1 lead in the five-match series after a hard fought 28-run win in the fourth game in Abu Dhabi on Friday night. De Villiers, whose team lost 4-1 in Sri Lanka in July, was delighted with the improvement against a Pakistan side he rates highly.
"I am proud of each and every one of the team, a series win away from home is never easy especially after defeat in Sri Lanka and against a world-class team like Pakistan," De Villiers said after the match.
Opener Quinton de Kock set the foundation with a maiden century while paceman Dale Steyn took a career best 5-25 to derail Pakistan, who were 228-5 at one stage after being set a 267-run target.
"I thought it was a very solid performance, it was a make or break game for us. We were excited but a little bit nervous at the prospect of what is lying ahead and the way the boys responded is magnificent," said De Villiers.
"It (series win) is a small step in the right direction, we definitely are not a great side yet, very far off still, but winning a series away from home is great," said De Villiers, who singled out Steyn for praise.
"Dale is an impact player for us. I bowled him when we felt like we could make inroads in Pakistan's batting. I never felt that it was getting out of our hands but I had a feeling that we needed to stay patient."
Steyn turned the game in South Africa's favour in the 47th over, claiming the wickets of Umar Akmal (22), Misbah-ul Haq (65) and Saeed Ajmal (nought) to bundle Pakistan out for 238, but the role played by De Kock was not lost on De Villiers either.
"I am very very proud of him, the way he came back after a disappointing series in Sri Lanka just tells you about his character and obviously about his talent, I always knew that he is a special talent," said De Villiers of the 20-year-old left-hander.
Meanwhile, Pakistan captain Misbah blamed his team's defeat on their lack of mental strength. "We need to be mentally strong, need to be calm because in such situations an over can change the game and that's what happened," said Misbah.
Misbah termed a narrow one-run defeat in the first match as the turning point of the series. "The turning point was the first game, had we won that the result would have been different," said Misbah of the match in Sharjah when Pakistan failed to chase a modest 184-run target.
"As a captain it's not being under pressure, it's disappointment that we cannot handle the pressure." The fifth and final one-day international will be played in Sharjah on Monday before the teams play two Twenty20 internationals on November 13 and 15 -- both in Dubai.