Morkel is No 4 in the International Cricket Council (ICC) bowling rankings in the one-day format, two places ahead of fellow paceman Steyn, but it is the spinners Robin Peterson, with 14 wickets, and Imran Tahir with 12 who have led the way in South Africa's progress to the quarter-finals.
Johan Botha, the off-spinner, has played what he described yesterday as a "holding role" and his input proved crucial in the narrow win over India when he was brought on midway through the innings to help slow the home side's explosive start.
India were all out for less than 300 and Botha ended with figures of none for 39 from nine overs.
"Our three spinners are a lot different from each other," Botha said. "Immy's [Tahir] a very attacking spinner, he's got us a lot of wickets in this tournament, so has Robin. I'm probably doing a bit more of a holding role and controlling the game from one side and they've been taking the wickets which is really good for us.
"Then we have world class seamers. All in all, we've got a really good bowling attack."
Botha, who started his career as a medium-pacer before switching to off spin in 2004, opened the bowling for the Proteas in Saturday's comprehensive defeat of Bangladesh, while Peterson took the role against England. It is a tactic which has also been used by several other teams, who have chosen to save overs for their quicker bowlers for when the ball is older and could reverse swing.
South Africa's ability to play spin could also be crucial against New Zealand on Friday, with Daniel Vettori expected to return to the opposition line-up, along with Kyle Mills, after the paceman missed two matches with injury.
England, who take on Sri Lanka in their quarter-final on Saturday, have unveiled their latest South African-born recruit, Jade Dernbach, a seam bowler.
Dernbach, born and raised in South Africa until he was 14, has been called up to replace injured bowler Ajmal Shahzad. The 6ft 2ins Surrey bowler, who turns 25 next month, follows Kevin Pietersen, Jonathan Trott, Craig Kieswetter and others as South Africans who have adopted England.
Sri Lanka's selectors are considering using three slow bowlers against England.
Muttiah Muralitharan, Ajantha Mendis and left-arm spinner Rangana Herath could all pose a tough challenge for the England batsmen on Saturday on a R Premadasa Stadium wicket which tends to keep low and slow.