21.   The momentum shift has many Republicans nervous.

22.   Four straight unforced errors cost Graf dearly in the tie-breaker which ended a series of early momentum shifts.

23.   The first set lasted for more than an hour and was full of momentum shifts as the two jockeyed for supremacy.

24.   The first set under sunny skies and little wind was strewn with breaks - five in ten games - as momentum shifts came quickly.