CORVALLIS, Ore., Oct. 15 (AP) -- Steve Francis and Kenny Thomas each scored 18 points as the Houston Rockets rallied from a 13-point third-quarter deficit to beat the Portland Trail Blazers 81-77 in an exhibition game Monday night.

Thomas, who had been shooting 35 percent in his first three games, scored six points during a late 8-0 run to help the Rockets (2-2) pull away from a 73-all tie in the final three minutes.

Derek Anderson scored 13 points and Shawn Kemp had 12 for the Blazers (1-3). Rasheed Wallace scored 11 before he fell on his back late in the third quarter, bruising his tailbone and an elbow.

Houston outscored the Blazers 17-6 over the last 5 1/2 minutes of the third quarter, then opened the fourth with a 9-2 run to take a five-point lead. The Blazers didn't regain the lead, and Thomas hit a pair of free throws and two baskets to put it away.

For most of the period, point guard Damon Stoudamire was Portland's only starter on the floor.

The game turned rough in the third quarter, when Wallace and Houston's Kelvin Cato left with injuries. Cato tried to block Dale Davis coming down the lane and fell on his right wrist. Minutes later Wallace leaped for a pass and fell on his lower back. Cato returned to start the fourth quarter with his wrist taped; Wallace stayed on the bench.

For the first time in the preseason, Blazers coach Maurice Cheeks left all his starters on the floor for the whole first quarter, and they took a 20-12 lead.

But both teams were sloppy in the first half, especially Houston. After Venezuelan rookie Oscar Torres scored the first seven points, the Rockets got just 27 in the next 22 minutes.

Portland took a 44-34 halftime lead when Anderson took an inbounds pass from Scottie Pippen with 1.9 seconds left, dribbled and sank a 35-foot shot from the top of the key as time ran out.

Ruben Patterson provided a lift in the second quarter, scoring six points on a putback and two dunks.