Sep 12, 2021; Jacksonville, Florida, USA; Green Bay Packers linebacker Za'Darius Smith (55) looks on the field during the fourth quarter against the New Orleans Saints at TIAA Bank Field. Mandatory Credit: Tommy Gilligan-USA TODAY Sports

The Green Bay Packers will be getting a boost to their pass rush for Saturday’s NFC division playoff game against San Francisco.

Outside linebacker Za’Darius Smith, who hasn’t played since Week 1, and defensive end Whitney Mercilus were activated off injured reserve by Green Bay on Friday.

To make room on the roster, Green Bay released defensive lineman Jack Heflin and cornerback Isaac Yiadom.

Smith was bothered by back issues during training camp and appeared in just 18 snaps in the season-opening loss to New Orleans. He subsequently had surgery and only recently returned to practice.

Last season, Smith was named second-team All-Pro after finishing fourth in the NFL with 12.5 sacks. He also recorded 52 tackles, 12 tackles for loss and four forced fumbles. In 2019, his first season with the Packers, Smith accounted for 55 tackles, 13.5 sacks and 17 TFL.

Signed by the Packers in midseason, Mercilus played in four games for Green Bay before tearing his biceps. He had five tackles and a sack with Green Bay. In six games with Houston, Merilucs had three sacks.

Over his 10-year career, Mercilus has 58 sacks, including 12 in 2015. He had 7.5 with the Texans in 2019 and four last season.

Green Bay tied for 16th in the NFL with 39 sacks during the 2021 regular season.

In addition to Smith, offensive tackles David Bakhtiari and Billy Turner are expected to play vs. the 49ers. Bakhtiari saw his first action of the season in Week 17, getting 27 snaps against Detroit. Turner hasn’t played since Week 14 due to a knee injury.

Cornerback Jaire Alexander also could suit up for the first time since Week 4, when he left that game with a shoulder injury.

Both Alexander and Bakhtiari are listed as questionable.

An undrafted rookie, Heflin played in four games for the Packers, recording one tackle while playing 17 snaps on defense and 13 on special teams.

Yiadom played in 16 games with one start. He had 10 tackles while appearing in 95 defensive snaps and 307 on special teams.

The Packers and 49ers meet in Lambeau Field on Saturday at 7:15 p.m.