Justin Smith, Ian Williams practice

SANTA CLARA, Calif. -- The San Francisco 49ers' defensive line suddenly looked a lot better Wednesday as starters Justin Smith, Ray McDonald and Ian Williams all practiced.

It was the first time Smith (offseason shoulder surgery) and Williams (broken leg) practiced all of training camp. McDonald (offseason bicep surgery) was nursing a minor leg injury for the past several days. The 49ers have been cautious with Smith and McDonald, and it's doubtful either will play a lot during the rest of the preseason.

Williams was taken off the PUP list Tuesday. Williams said earlier Wednesday that his return to the field is still a process, but he participated fully later in the practice.

The reinforcements are needed. The 49ers finished Thursday's preseason opener at Baltimore with four healthy defensive linemen.