raonic called a trainer after dropping serve for the second time to trail 5-2 in the first .
raonic had to retire from his quarter-final showdown with berdych due to a troublesome foot injury .
berdych , who has yet to lose a set this week , will face either grigor dimitrov or gael monfils in the semi-finals of the clay-court masters tournament .
eight-time champion rafael nadal will play david ferrer , and top-ranked novak djokovic will face marin cilic .