SANTA CLARA -- While David Akers and Billy Cundiff began their kicking derby Thursday, defensive tackle Justin Smith returned to 49ers practice for the first time since partially tearing a triceps tendon Dec. 16.

Smith wore a black brace on his left arm and showed no discomfort while engaging in light drills with fellow linemen during the media's 30-minute access window.

After missing the 49ers' final two regular-season games, Smith has vowed to come back for the playoffs, which begin for the 49ers on Jan. 12 when they host a divisional-round game.

Smith began his first drills quite focused as linebacker Patrick Willis unsuccessfully tried to gain his attention by shouting Smith's nickname, "Cowboy."

Another spectacle Thursday was the kicking competition the 49ers have started between Akers, the embattled incumbent, and Cundiff, who was signed Tuesday.

During the warm-up period, Akers made only 16 of 21 field-goal attempts, missing wide right from 53, 52, 43, 43 and 48 yards. Andy Lee held on all of Akers' attempts.

Cundiff connected on 10 of 12 attempts, missing wide right from 45 and 52 yards. He was 7 of 8 when Lee held for him.

While Akers and Cundiff took turns kicking on the 49ers' artificial surface, several defensive players paid close attention, as did coach Jim Harbaugh, general manager Trent Baalke and special-teams coordinator Brad Seely.

On the injury front, the 49ers appeared to be at full strength. Many players who recently wore no-contact jersey had shed those for Thursday's practice, including linebackers Aldon Smith and Ahmad Brooks, cornerback Tarell Brown and fullback Bruce Miller.