After an indifferent start to the World Cup, Steyn marked his 100th one-day international with 2-39 in the 201-run mauling of Ireland at the Manuka Oval on Tuesday.
Bowling with pace and venom, Steyn sent back opener Paul Stirling for nine and then had danger man Ed Joyce picked up for nought as the Proteas claimed their third win in four games.
However, Steyn still has relatively modest figures of 5-182 from the four games, having been dominated by India's batsmen at the MCG, going for 1-55 in his team's 130-run defeat.
"I've got no worries about Dale at all," insisted de Villiers. "He's going to win us a couple of crucial games in this tournament.
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"He runs in with a lot of energy, intensity. He bowled with pace again against an Ireland team that it's very easy to sort of sit back and go 'I don't really have to give it all my all here, we just have to relax; we've got 400 on the board'.
Abbott, meanwhile, has seized his opportunity to give South Africa a selection headache before their next Pool B match against Pakistan in Auckland on Saturday should first-choice Philander recover from the hamstring injury he suffered against India on February 22.
The 27-year-old Abbott has played just 13 ODIs for the Proteas since his debut two years ago and his 4-21 against Ireland represented his best figures.
Abbott, a barrel-chested right-arm seamer from KwaZulu-Natal, has also had to be patient in the Test arena having figured in just three matches.
"He's played a lot of cricket domestically. He's a very experienced campaigner, and he shows that he plays with his heart on his sleeve," said de Villiers.
"He's got a lot of passion for the game, a lot of passion for the team. He's always one of those guys that when he's in the side, you know what you're going to get from him. You're going to get 100 percent commitment.