The Ryder Cup golfer had a second round of 67 for a nine-under par 135, which gave him a lead of three shots at the half-way stage over Anders Forsbrand and Scotland's Gordon Brand Jnr.
He might not have been in such a happy position, however, without the help of Mikael Eriksson, the European Tour official, who helped a stricken Clark on to his electric buggy at the sixth hole and ferried him to the nearest toilets on the King's links.
'I was doubled up with stomach cramps,' Clark said after recovering to shoot four birdies in an inward 32 and, for the second week running, give himself a chance of a first Tour victory since 1988.
'I don't think it is anything I have eaten here that has upset me, but I have been on a diet of bread and fruit since I arrived. I am pretty sure that I have picked up a strain of the virus that is affecting my wife and son at home.'
Clark has scores of 67 and 68 behind him, just as he did last week at the Madeira Open, where he was second to Sweden's Mats Lanner. 'I am not even thinking about victory yet.'
Forsbrand, who had four twos in his 68 for a total of 138, looked at one stage as though he would head a Scandinavian takeover of the leaderboard. Swedes were filling the first five places until Clark and Brand got to work.
Robert Karlsson, who had 72 for 140, was also six under until he lost a ball at the sixth and slipped back alongside Peter Hedblom, one of last week's runners-up.
Pedro Linhart, the Spanish newcomer from the Canary Islands, had 68 to move to the fringe of the top 10 alongside the Australian-raised Gabriel Hjertstedt and Nick Henning, of South Africa.
Henning, from Johannesburg, is making his first appearance on the European circuit. He was rookie of the year in the Republic last season and was runner-up to Tony Johnstone in the recent Zimbabwe Open.
MOROCCAN OPEN (Agadir) Leading second round scores (GB or Irl unless stated): 135 H Clark 68 67; 138 G Brand Jr 70 68, A Forsbrand (Swe) 70 68; 139 M Roe 71 68; 140 R Karlsson (Swe) 68 72, J Sewell 68 72, P Hedblom (Swe) 68 72, J Robson 71 69, J Van de Velde (Fr) 72 68, P Walton 69 71; 140 G Hjertstedt (Swe) 69 72, D Williams 74 67, P Linhart (Sp) 73 68, N Henning (SA) 71 70, J Robinson 71 70, J Hall 71 70; 142 S Richardson 74 68; 143 P Mayo 70 73, S Grappasonni (It) 70 73, P Fluke (Swe) 75 68.
Andre Cruse, who is partially sighted and relies on his caddie to line up his putts, was in second place after the second round of the ICL International tournament in Verwoerdburg, South Africa, yesterday. A 66 gave him an 11-under- par total of 133 at half-way, three strokes behind the leader, Zimbawe's Nick Price.Reuse content