Hit by Flu, Joyner Bugs Moon, Oilers in the Eagles’ 13-6 Victory : Pro football: Linebacker leads ferocious defense that doesn’t permit potent Houston offense to score a touchdown.

When you have Seth Joyner--healthy or unhealthy--and the NFL’s best defense, you don’t need much of an offense.

The Philadelphia Eagles proved that Monday night, forcing five fumbles, two of them recovered by Joyner, to stay in the midst of the NFC playoff race with their fifth consecutive victory, a 13-6 decision over the Houston Oilers.

With help from third-string quarterback Jeff Kemp, the latest emergency replacement in a season of emergencies, it was enough to keep the Oilers from clinching their first AFC Central title.

“We can dominate on defense,” said Joyner, who forced two fumbles, recovered two and had two of Philadelphia’s four sacks of Warren Moon despite vomiting from flu in the locker room before the game.

“When we hit on all cylinders, the sky’s the limit for our defense. When our front four plays well, our defense is unstoppable.”

Houston (9-4) remained in good position for its first division title since 1967. Either a Houston victory or a loss by Cleveland in the remaining four games will clinch the division title, although the Oilers lost almost any shot they have of getting the home-field advantage throughout the AFC playoffs.

The Eagles (8-5) tied Dallas and Atlanta in the NFC wild-card race.

Not only did they hold an offense that is second in the league with 392 yards a game to 247, but they never let the Oilers inside the Philadelphia 24-yard-line--which they reached on the final series of the game. It was the first time in 33 games going back to 1989 that Houston didn’t score a touchdown.

Kemp relieved Jim McMahon, who suffered a hyper-extended right elbow, and threw for the game’s only touchdown, a 24-yard pass to tight end Keith Jackson.

It came 1 minute 29 seconds after Roger Ruzek had tied the score, 3-3, midway through the third quarter after Joyner recovered a fumbled snap by Moon and returned it to the Oilers’ eight-yard line.

The first half was scoreless until Al Del Greco’s field goal on the last play of the half.

“What can you say?” asked Coach Jack Pardee of the Oilers. “They’re No. 1 on defense, No. 1 vs. the rush and No. 1 vs. the pass. They didn’t hurt their stats any tonight.”

They allowed the Oilers inside the 25 only once--on the final series, when Moon, who was 24 of 46 for 262 yards, threw three incomplete passes into the end zone from the 24-yard line as time ran out. Until that final drive against a prevent defense, the Oilers managed only 185 total yards.

Kemp, 10 of 17 for 84 yards, also directed a drive that consumed 10:05 of the fourth quarter to set up a 29-yard field goal by Ruzek.