Trevor Siemian put the 49ers away -- and might have put away the race for the Broncos' quarterback position.
Siemian went 8 of 11 for 93 yards and a touchdown to lead Denver to a 33-14 victory over San Francisco in Santa Clara, Calif., on Saturday, spoiling the preseason home opener for new 49ers coach Kyle Shanahan.
But the competition between the quarterbacks might have effectively ended Saturday, as Lynch looked unsettled and didn't complete any passes longer than 7 yards, while Siemian pushed the ball downfield and hit wide receiver Jordan Taylor for a 19-yard touchdown that pushed the Broncos' halftime lead to 20-0.
Lynch left with a 13-0 lead, but that was built mostly by 49ers' miscues. Four San Francisco turnovers led to all 20 of Denver's first-half points. Lynch finished with 39 yards on 9-of-13 passing, averaging only 3 yards per attempt.
The Broncos started all four of their first-half scoring drives from beyond their 45-yard line, and twice took over possession in 49ers territory, including at the San Francisco 11 after a Riley Dixon punt bounced off the leg of 49ers safety Jaquiski Tartt.
Denver safety Will Parks recovered the loose ball and the Broncos scored four plays later on a 1-yard run by C.J. Anderson to open the scoring.
San Francisco's offense found some success moving the ball against the Broncos during joint practices at the 49ers' facility this week but could not replicate that in Saturday's game.
Turnovers, penalties and an inefficient running game often forced quarterback Brian Hoyer into long-yardage situations, and although he completed eight of his 11 passes for 89 yards, the 49ers ran only four plays in Broncos territory during Hoyer's four possessions.
Rookie backup quarterback C.J. Beathard entered the game late in the second quarter and finished with 110 yards and a touchdown on 7-of-12 passing.
The Broncos won comfortably despite playing the game without eight starters: outside linebackers Von Miller and Shane Ray; wide receiver Emmanuel Sanders; center Matt Paradis; defensive ends Jared Crick and Derek Wolfe; safety T.J. Ward; and inside linebacker Brandon Marshall.
Several other key defensive players, most notably All-Pro cornerbacks Chris Harris Jr. and Aqib Talib, Pro Bowl safety Darian Stewart and nose tackle Domata Peko, were pulled after one quarter.