Al Horford grabbed 13 rebounds and dished four assists as the Atlanta Hawks pulled off an upset over the top-seeded Chicago Bulls in Game 1 of the semifinals of the NBA playoffs.

The 6-feet-10-inch center, who had to battle with the Bulls' imposing frontline all night, more than held his own in the Hawks' 103-95 win.

Game 2 in Chicago is set for Wednesday night.

The 24-year-old Dominican, who was born in Puerto Plata, played 37 minutes and scored nine points. He also blocked two shots.

He has averaged 11.5 points per game in the playoffs.

Pau Gasol, meanwhile, and his Lakers were less fortunate. Los Angeles, despite a solid effort from its 7-foot center, dropped Game 1 of the western semifinals to the Dallas Mavericks, 96-94.

The 30-year-old Spaniard scored 15 points and grabbed 11 boards. He also dished out seven assists and blocked a shot.

He turned the ball over three times, however.

After a slow start, Gasol has picked it up in the playoffs, averaging nearly 14 points per game in seven contests.

The Lakers, two-time defending NBA champions, will try to even the series Wednesday night at home.

For the third-seeded Mavericks, guard J.J. Barea, who is Puerto Rican, scored eight points and had five assists in 14 minutes.

The Associated Press contributed to this story.

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