Eoin Morgan hammered a career-best 148 and led England to 397 for 6 against Afghanistan.
After the stutter against Pakistan, England have motored along nicely and look to erase any doubts of a possible shock defeat.
Quinton de Kock scored 68 for South Africa as they coasted home in the 28th over.
Tahir ended with figures of four for 29 in his seven overs, while Morris returned with exquisite numbers of three for 13 in his 6.1 overs.
Winless so far in the tournament, both South Africa and Afghanistan will be eagerly looking to tick the victory box when they square off.
Naib revealed that the legspinner is doing a lot better and that he might be taken to a hospital for further tests.
Relive all the action in pictures from Taunton where Kane Williamson and James Neesham led New Zealand to a convincing seven-wicket victory against Afghanistan.
The ball bounced off Rashid's helmet and hit the stumps, but when he left the pitch after being dismissed he looked clearly groggy.
While New Zealand retained the same playing XI, Afghanistan made three changes to their playing XI.
New Zealand's nervy win against Bangladesh was indication that Afghanistan may after all, have a chance to pull off a surprise.