Updated

Oklahoma City, OK (SportsNetwork.com) - Serge Ibaka's tip-in came a blink after the overtime buzzer sounded, and the Memphis Grizzlies stole Game 5 of their Western Conference quarterfinal series against the Oklahoma City Thunder with a dramatic 100-99 victory on Tuesday.

These evenly-matched clubs came in tied at 2-2 and played an extra five minutes for an unprecedented fourth straight game after Russell Westbrook stripped Mike Conley at the top of the key and went in for an uncontested layup with 4.0 seconds left in regulation.

Kevin Durant had a chance to even things again late in OT, but after hitting the first of his two free throw attempts with 27.5 ticks left, referee Joey Crawford physically stopped the 87-percent free throw shooter from attempting his second try to fix a problem at the scorer's table.

Durant drew iron when play resumed, then found the back rim on a fallaway 28- footer as time ticked away. Ibaka's acrobatic follow went in, but after a review, it was determined his hand was on the ball just as the clock hit zero.

"I had a good look at it and I thought it was good when it left my hand," Durant said of the fallaway. "And then Serge's follow shot was just late. It was a tough finish but we've got to come back."

Mike Miller scored six of his team-high 21 points in overtime while Zach Randolph and Marc Gasol each recorded double-doubles for the Grizzlies, who can send the Thunder home from the postseason for the second straight year with a win in Memphis on Thursday.

"We get it out of the mud, we grind and we're underdogs. It's what we do," Randolph said.

Westbrook finished with a triple-double of 30 points, 13 assists and 10 rebounds, while Durant chipped in with 26 points and eight boards for Oklahoma City, which turned it over 17 times and shot under 40 percent (39.1) for the fourth consecutive contest.

Staring at a 20-point deficit with 15 1/2 minutes remaining in regulation, the Thunder switched into the gear that made them the No. 2 seed in the West.

Whereas Reggie Jackson came off the bench as the unlikely hero in Game 4's OT win, Caron Butler surprisingly stepped up with eight of his 15 points during a 22-4 Oklahoma City run that spanned into the fourth quarter.

Butler's bucket off an offensive rebound made it a 76-74 game, and Durant's 3- pointer with 6:46 left in the fourth gave the hosts their first, and what proved their only, lead of the night at 79-78.

Memphis answered with the next five points and led 87-82 before Butler converted a four-point play with 2:40 on the clock. After trading free throws, the Thunder had three straight empty possessions and trailed 90-88 after Tony Allen made the first of two free throws inside the final minute.

Allen missed the second free throw, and Tayshaun Prince tapped the offensive rebound back to Gasol as the Grizzlies called timeout with 20.3 showing.

Instead of fouling, the Thunder opted to play defense, and Westbrook came away with a clean steal of Conley at the top of the key as four seconds remained by the time his tying layup went through.

Randolph's basket at the other end proved too late, and it was even at 98-98 prior to Conley capping his 17-point effort with a go-ahead layup with 62 seconds to play.

Allen was whistled for a loose ball foul on Durant, and Crawford's perceived icing preceded a Miller miss that gave the Thunder one last chance that came fractions of a second too late.

Memphis scored 10 of the game's first 12 points, six coming from Randolph as he made his first six shots from the floor en route to a 13-point first half.

Ibaka beat the first-quarter buzzer with a 3-pointer to pull Oklahoma City within 30-25, but a 9-0 Grizzlies run extended the visitors' lead to 48-36 midway through the second.

The Thunder connected on only two field goals over the final eight minutes of the second quarter and were in a 55-43 hole at halftime. They found themselves in a 20-point deficit when Beno Udrih pulled up for a jumper for a 72-52 spread with 3 1/2 minutes remaining in the third.

Game Notes

Oklahoma City guard Derek Fisher passed Robert Horry for the most playoff appearances in NBA history with 245 ... The Thunder are the only Western Conference team to advance past the first round in each of the last three seasons ... Durant (1,686 points) past Gary Payton (1,668) for the most career playoff points scored in franchise history ... Randolph went for 20 points and 10 boards while Gasol had 11 with 15 ... Ibaka also posted a double-double of 15 points and 12 rebounds.