21st May: Chennai Super Kings v M. Indians, 14:30 GMT
24th-28th May: 2nd Test, Headingley
Morkel will miss the two matches after suffering a side strain playing for the Chennai Super Kings in the Champions League, a competition they went on to win in Johannesburg.
However, Cricket South Africa (CSA) expect Morkel to be fit in time for the three-match One-Day International series, which gets underway on 15th October.
“We are anticipating that Albie will be fit in time to take his place in the three-match MTN ODI series that starts next week,” selection convener Andrew Hudson said.
McLaren, who also featured in the Champions League for the Mumbai Indians, recently took eight wickets to help the Chevrolet Knights beat the Nashua Dolphins in the opening round of the 2010/11 SuperSport Series.
The Twenty20 matches, in Bloemfontein and Kimberley, are to be played on 8th and 10th October.
McLaren has played one Test, ten ODIs and four Twenty20 Internationals for South Africa, taking five for 19 in his second-to-last appearance against the West Indies in May.
South Africa T20I squad: Johan Botha (captain), Loots Bosman, JP Duminy, Colin Ingram, Heino Kuhn, Ryan McLaren, David Miller, Morne Morkel, Wayne Parnell, Robin Peterson, Graeme Smith, Juan Theron, Lonwabo Tsotsobe
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