SANTA CLARA -- The 49ers on Monday activated veteran tight end Garrett Celek from the physically unable to perform list in order to be available just hours later to face the Seattle Seahawks at Levi's Stadium.

The 49ers released cornerback Dontae Johnson to make room for Celek on the 53-man roster.

The 49ers do not expect Pro Bowl tight end George Kittle to be available due to knee and ankle issues. Kittle has not practiced since sustaining his injuries on Oct. 31 against Arizona. The 49ers listed Kittle as doubtful for Monday's game.

Celek, 31, underwent back surgery in June and was on the team's physically unable to perform list through the first nine weeks of the season. He began practice last week. Celek joins Ross Dwelley and Levine Toilolo as the team's healthy tight ends for Monday's game.

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Celek has made 30 starts in his NFL career. He has 82 receptions for 1,104 yards and 12 touchdowns since coming to the 49ers as an undrafted rookie from Michigan State.

Kittle leads the 49ers with 46 receptions for 541 yards and two touchdowns.