The duo have agreed to deals at Lord's after the County missed out on initial targets Ashley Noffke, the Australian paceman who played seven County championship matches for them last summer, and Indian spinner Anil Kumble.
Queenslander Noffke decided prolonged rest was the only cure for a chronic back problem, while pre-Christmas negotiations with Kumble were scuppered by the Board of Control for Cricket in India's refusal to release him.
Hayward, who claimed 67 first-class victims at an average of less than 23 for Worcestershire last summer, was only halfway through his two-year deal at New Road. But the Midlands County mysteriously pursued and signed former player Andy Bichel, leaving Hayward surplus to requirements.
The 26-year-old made noises about making himself available for South Africa again at the end of last season, having taken 50 wickets in a stop-start career of 14 Tests.
But that failed to materialise, and the cold-shouldering by Worcestershire led to his management company athletes1 seeking alternative employers. This deal appears to suit all parties, with Worcestershire welcoming back the popular Bichel and Middlesex inheriting genuine hostility with the new ball.
Undoubtedly one of the fastest bowlers on the planet, Hayward's temperament can sometimes be as wayward as his radar. But he has a proven track record, as does Klusener - recently back in the international fold after a year's exile.
Klusener, 32, had a brief stay on the county scene with Nottinghamshire in 2002 and will be available between May and July for Middlesex, with international call-ups dictating whether he stays for the full campaign.
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