Carson Whisenhunt overcame a rocky start as he allowed four runs over five innings in his major-league debut, but the Giants’ losing streak hit four games as they fell to the Pittsburgh Pirates 6-5 on Monday night at Oracle Park. With Thursday’s trade deadline looming, San Francisco has lost 10 of its last 12 games.

SAN FRANCISCO — With their rotation in a bind and the losses beginning to pile up, the San Francisco Giants will seek a boost from their top pitching prospect Monday. The team will promote left-hander Carson Whisenhunt from Triple-A Sacramento to make his major-league debut with a home start against the Pittsburgh Pirates.

SAN FRANCISCO — With the Giants’ rotation in flux following Hayden Birdsong’s demotion and Landen Roupp’s injury, manager Bob Melvin announced following Sunday’s 5-3 loss to the New York Mets that top pitching prospect Carson Whisenhunt will start on Monday and make his major-league debut.