The 12-year-old is trying to become the youngest person to ever run a marathon on all seven continents.
The British runner wants to break his marathon personal best of 2:10 he ran three years ago.
The 18-year-old American finished in a personal best 8:58.48 at Hayward Field.
The Boston Marathon champion has been runner-up at this race twice in the past.
The British runner is still on target to compete at the European Championships next month.
American Maggie Schmaedick finishes 12th overall in front of her home fans.
Elsewhere, American Sabrina Southerland finishes eighth in her heat.
The 29-year-old discusses her recent American record in Monaco, her future plans and more.
Americans Brendan Shearn and Jonathan Green finish 15th and 24th.