For two games, the Spurs made life without Tony Parker look easy. With their injured All-Star point guard sidelined in street clothes, they blasted Detroit and Chicago by a combined 57 points, looking suspiciously like the same dominant team that had raced to the top of the NBA standings. Then came Friday night at the AT&T Center, a visit from the Portland Trail Blazers, and the cold slap of reality in the form of a 136-106 loss. If it makes the Spurs feel any better, with the way Portland played in dealing them the most lopsided home defeat of the Tim Duncan era, not even a healthy Parker — cloned five times over — could have saved them. “We felt bad, embarrassed after the game,” center Tiago Splitter said. “We’re not used to this.” Behind 35 points and nine assists from point guard Damian Lillard, who has rendered the NBA’s Rookie of the Year award a one-man race, the Blazers rattled off 79 points in the second half and 46 in the fourth quarter to stun the Spurs (48-15). It was the Spurs’ largest margin of defeat at home since a 125-92 loss to Toronto on Feb. 19, 1997, the season before Duncan arrived, and their largest ever at the AT&T Center, which opened in 2002.