The Boston Celtics and San Antonio Spurs will try to convert 3-1 first-round leads into second-round berths Tuesday night, with both teams carrying short odds after decisive Game 4 wins reshaped their respective series.

Boston hosts the Philadelphia 76ers at 7 p.m. ET at TD Garden, while San Antonio hosts the Portland Trail Blazers at 9:30 p.m. ET at Frost Bank Center. The NBA’s official postseason schedule lists both games for ESPN, and both matchups arrive with the higher seed holding three wins and a chance to avoid a longer, more volatile series.

The betting angle is straightforward: oddsmakers have treated the Celtics and Spurs less as narrow home favorites and more as teams expected to finish the job. ESPN’s playoff bracket page showed Boston as a double-digit Game 5 favorite over Philadelphia, while market listings tracked by betting outlets showed San Antonio as a heavy favorite over Portland. The precise numbers can move by sportsbook and time of posting, but the direction of the market is clear: bettors are being asked to pay a premium to back either favorite on the moneyline.

Boston created that position with its most complete game of the series Sunday, beating Philadelphia 128-96 in Game 4. Reuters reported that Payton Pritchard scored a playoff career-high 32 points off the bench, Jayson Tatum added 30 points, 11 assists and seven rebounds, and Jaylen Brown had 20 points. The Celtics also made 24 3-pointers, a franchise playoff record, while winning the rebounding battle 51-30.

For Philadelphia, the issue is not merely that it trails 3-1. It is the way Game 4 unfolded. Joel Embiid returned after being cleared following an appendectomy and still produced 26 points and 10 rebounds, but the Sixers could not keep pace with Boston’s volume shooting, spacing or depth. Tyrese Maxey scored 22 and Paul George added 16, yet Philadelphia’s offense became increasingly dependent on difficult possessions while Boston generated cleaner looks across multiple lineups.

That is why the Celtics’ Game 5 pricing is tied as much to matchup control as to home court. Boston has multiple creators, a high-volume 3-point profile and enough defensive length to make Philadelphia work late in the shot clock. If Pritchard’s Game 4 was the outlier on the scoring sheet, the broader concern for the Sixers is that Boston did not need an unusually efficient night from every starter to win by 32.

The Spurs’ path to their own close-out opportunity has been more dramatic. San Antonio beat Portland 114-93 in Game 4 after trailing by 19 late in the first half. Reuters reported that the Spurs outscored the Trail Blazers 73-35 in the second half, with Fox scoring 28 points and Wembanyama adding 27 points, 11 rebounds, seven blocks and four steals in his return from concussion protocol.

Wembanyama’s status had been a major variable earlier in the series, but Game 4 changed the tone. With him back protecting the rim and disrupting passing lanes, San Antonio’s defense looked far closer to the version that earned the West’s No. 2 seed. Fox gave the Spurs a late-clock engine, and rookie guard Stephon Castle supplied another source of pressure with 16 points and eight assists.

Portland’s task is to turn one strong half into a full road elimination performance. Deni Avdija, Jrue Holiday and Jerami Grant gave the Trail Blazers enough scoring to build a lead in Game 4, but turnovers and defensive breakdowns erased it quickly. Local coverage in San Antonio noted that Game 5 will be played at Frost Bank Center with playoff giveaways and a full home-arena push, adding another layer to a matchup already leaning toward the Spurs in the market.

Neither favorite is guaranteed a clean finish. The NBA’s first round has already shown how quickly injuries, shooting variance and foul trouble can alter a series. Philadelphia still has top-end talent in Embiid, Maxey and George. Portland has enough athleticism and guard play to pressure San Antonio if the Spurs open slowly again. The market’s view is not that the underdogs lack paths, but that both would need sharper execution than they showed in their most recent second halves.

For bettors and fans, the difference between the Celtics and Spurs close-out spots may be style. Boston’s favorite status is rooted in proven playoff continuity, perimeter shot volume and a roster that can punish defensive mistakes quickly. San Antonio’s is rooted in momentum, home court and the two-way ceiling of Wembanyama paired with Fox’s shot creation.

Tuesday’s results will also affect the second-round calendar. A Boston win would allow the Celtics to rest and prepare without sending the series back to Philadelphia. A Spurs win would deliver San Antonio’s first postseason series victory of the Wembanyama era and keep the franchise from risking a Game 6 in Portland. For the Sixers and Trail Blazers, the assignment is simpler but more severe: win once on the road, or the offseason begins.

That is the shape of the board entering Tuesday night. The Celtics and Spurs have the leads, the venues and the odds. Philadelphia and Portland have urgency, but little margin left.