Sapporo, Japan ? Now comes the hard part.

The U.S. closed a perfect week of group play Thursday night by routing Senegal, 103-58. But with more demanding games ahead, one stumble and this young but talented team will be out of the hunt for the country’s first FIBA world championship title since 1994.

The U.S. will open the tournament’s medal phase against Australia, the fourth-place finisher in Group C, on Sunday in Saitama.

“We came over here to win the gold,” center Dwight Howard said. “The first game is Sunday, and we can start off on the right note.”

The reward for winning Group D is substantial: The Americans won’t have to face Argentina or Spain until the final. But there’s a lot of basketball to be played before then.

“There will be some surprises,” said Senegal’s Makhtar N’Diaye, who played in college at Michigan and North Carolina. “Argentina and Spain can bring a lot of havoc.”

The U.S. faced only one tough test in Group D – Wednesday’s 94-85 victory over Italy, which finished second. The competition will improve dramatically, although some teams aren’t familiar to the Americans.

They know Australian center Andrew Bogut, who plays for the Milwaukee Bucks. And they’re well acquainted with Dallas star Dirk Nowitzki, whose German team could meet the U.S. in the second round. Nowitzki lit up Angola for 47 points in Germany’s 108-103 triple-overtime victory Thursday.

Team USA's Carmelo Anthony, standing, cheers on his team from the bench during a 103-58 victory over Senegal in the World Basketball Championship. The U.S. rolled to the victory Thursday in Sapporo, Japan. Other U.S. players are, from left, LeBron James, Chris Paul and Dwight Howard.

This is where the new U.S. scouting department, created by managing director Jerry Colangelo, should pay dividends.

“We’re going to be familiar with some of the players, but not the teams,” scouting director Rudy Tomjanovich said.

As Tomjanovich’s scouts know, a number of interesting story lines have developed as the tournament moves to Saitama.

One of the big surprises is Angola, which finished 11th in the 2002 worlds in Indianapolis. The Angolans’ loss to Germany didn’t take the luster off an impressive first-round showing.

“They have exceptional quickness and great shooters at every position and can really spread you out,” German coach Dirk Bauermann said. “I thought we did an exceptional job of defending them. Give us credit. We did a good job offensively and defensively.

“They really test you individually and as a team,” Bauermann added. “The combination of their individual ability and skills and their athleticism make them very tough.”

Angola plays an exciting, up-tempo style, averaging 90.2. Small forward Olimpio Cipriano burned Germany for 33 points, hitting 6-of-12 three-point shots.

China is another up-and-comer. Three games into the tournament, the Chinese looked dead. After losing to Italy by 15 points and the U.S. by 31, the Chinese lost by three points in overtime to Puerto Rico. But the Chinese bounced back to beat Senegal and then stunned Slovenia 78-77 Thursday on a buzzer-beating three-pointer by Wang Shipeng.

With those victories, the Chinese finished fourth in Group D and lived up to center Yao Ming’s guarantee that they would reach the second round.