PRO FOOTBAL

Only the defending Super Bowl champion Pittsburgh Steelers avoided being upset during a shocking weekend of playoff games. With an impressive 34-14 mauling of Miami in one AFC semifinal, the Steelers advanced to Sunday's conference championship game against Houston, a surprise 17-14 winner over San Diego. In the NFC, Tampa Bay toppled Philadelphia 24-17 to move into that circuit's championship game against Los Angeles, which knocked off Dallas 21- 19 .

* Houston's Vermon Perry emerged as the top individual star of the week as he came up with the big defensive plays the Oilers needed against perhaps the game's most explosive passing team. Perry accounted for four of Houston's five interceptions and also blocked a Mike Wood field-goal attempt, which he ran back to the Charger 28 to set up a field goal. Perry's alert play keyed an outstanding defensive effort, so important to the injury-wracked Oilers, whose offense was without starters Earl Campbell, Dan Pastorini, and Ken Burrough. Filling in for the injured Pastorini, second-year QB Gifford Nielsen hit Mike Renfro with the game-winning, 47-yard TD pass in the third quarter.

In setting up their second straight AFC title showdown with Houston, Pittsburgh zapped Miami with 20 first-quarter points. Steeler QB Terry Bradshaw completed 21 to 31 passes and Franco Harris rumbled for 83 yards in this awesome tuneup.

* Ricky Bell fueled Tampa Bay's offensive attack as he gained 142 yards while carrying a playoff- record 38 times and scoring two TDs. The Buccaneers put 17 points on the board in the first half, then let their defense hold off the Eagles most of the rest of the way.

Los Angeles, a team which has experienced its share of playoff frustration, tasted victory this time when Billy Waddy caught a tipped Vince Ferragamo pass and raced 50 yards with for the winning touchdown late in the fourth quarter.