
The Romanian went up a break at 2-1 in the first set after her Czech opponent double-faulted, and Halep reeled off the next six games behind confident groundstrokes and precise serving.
The tournament’s 2015 champion was never really pushed, winning 55 points to Martic’s 21.
The unseeded Martic had notched impressive wins over 28th-seeded Ludmilla Samsonova and US Open champion Emma Raducanu en route to the quarterfinal, but appeared to run out of gas under sunny skies in the California desert.
Next up for Halep is either big-serving American Madison Keys or third seeded Iga Swiatek, who play their quarterfinal later today.