PHOENIX (Ticker) -- The Phoenix Suns face a virtual must-win situation Tuesday when they host the San Antonio Spurs in the second game of the Western Conference Finals.

The top-seeded Suns relinquished home-court advantage in Game One on Sunday, dropping a 121-114 decision to the second-seeded Spurs. Reserve Brent Barry, who had averaged just 6.6 points in the first two rounds, scored 13 of his 21 in the fourth quarter, when San Antonio scored 43 points on 72 percent (16-of-22) shooting.

Tim Duncan had 28 points and 15 rebounds and Tony Parker added 29 points for the Spurs, who finished the regular season with the league's best home record at 38-3, making it very difficult for the Suns to rally from a potential 2-0 series deficit.

Amare Stoudemire scored 41 points and MVP Steve Nash had 29 and 13 assists for Phoenix, which trails in a series for the first time this postseason.

To even the series at a game apiece, the high-flying Suns likely will have to get their running game going. San Antonio, which led the NBA in points allowed during the regular season, limited Phoenix - the league's top offense - to just six fast-break points. The Suns had averaged 19.5 fast-break points through the first two rounds.

Phoenix will once again be without swingman Joe Johnson, who will miss his sixth straight game since fracturing his orbital bone in Game Two of the Western Conference semifinals against Dallas.

Johnson was examined Monday, but is not expected participate in a full practice until Thursday.

The series will shift to San Antonio for Game Three on Saturday.