The Spurs had hoped their home-heavy March schedule would set them up for an April stretch run devoid of pressure. Now, Tony Parker’s sprained left ankle has added importance to every remaining game this month. Still three games ahead of the Thunder (and with two fewer losses) in the race for best record in the Western Conference, the Spurs don’t want to get to a difficult April schedule having to scrap to hold on to one of the top two spots. As for this month, they face eight playoff-bound teams among the 11 games at the AT&T Center. That’s why tonight’s game against the Pistons has become a must-win. Lose a couple to some of the league’s sub-.500 teams, and April easily could turn into a struggle to retain home-court advantage in the first round. The Spurs have been resilient all season, thriving despite injuries that have sidelined Tim Duncan (eight games), Kawhi Leonard (20 games), Manu Ginobili (10 games) and Stephen Jackson (16 games, plus three for personal reasons).