PHOENIX - The Phoenix Suns have been plagued all season by letdowns after big wins. Kevin Johnson didn't let that happen last night.

Johnson scored 18 of his 31 points in a lopsided first half and then helped his team avert a fourth-quarter collapse as Phoenix beat the Utah Jazz 107-100.

''That's been our big problem all year - letdowns,'' said Johnson, who also had 10 assists. ''We beat Chicago here (106-96 on Feb. 6) and then lost to Seattle a few nights later.

''We were coming off a big win Tuesday night over San Antonio. Now, we have to keep the momentum going as the playoff get closer.''

The win was the sixth straight at home for the Suns and moved them ahead of idle Portland for the No. 6 spot in the Western Conference playoff race. Phoenix plays Western Conference leader Seattle on Friday.

''Now we get to see what we're made off,'' said Charles Barkley, who had 15 points and 11 rebounds but missed 9 of his 12 field goal tries. ''We'll be playing the best team in the West on the road and that's when we really have to judge ourselves.''

Utah lost its third game in a row for the first time since November 1994 and fell four games behind San Antonio.

''For whatever reason, we didn't come out and play with any fire,'' said John Stockton, who had 17 points and 16 assists. ''Barring major changes, we're probably locked into the No. 3 spot for the playoffs. If we play Phoenix in the first round, we have to play better than this if we want to beat them.''

The Jazz trailed 59-38 late in the first half and 85-73 entering the fourth period.

Jeff Hornacek, who had 23 points, brought Utah within 98-96 on a baseline jumper with 2:53 remaining. But the Jazz only made two more field goals the rest of the way as Johnson and rookie Michael Finley took over down the stretch.

Finley hit a scoop shot in the lane with 2:01 left and Johnson converted a driving layup to make it 104-96 with 1:18 to go.

Finley, who finished with 17 points, drove the baseline for a reverse layup and a 106-98 advantage with 35 seconds left as Phoenix went three games over the .500 mark for the first time this season.