Rookie Ben Spies provided an indication of his threat on the World Superbike title back-to-back race wins in Qatar on Saturday.

The 24-year-old American had already secured pole position and a fastest-ever circuit of the Losail track before sweeping to a pair of impressive wins today.

Veteran duo Noriyuki Haga and four-time champion Max Biaggi were forced to settle for second and third respectively in both races, as they were left in the wake of Spies' Yamaha.

Spies was most impressive in Race Two when he quickly opened a gap on his more experienced rivals before producing a nerveless display out front to cross 1.274 seconds ahead of Haga.

The American's stock is quickly rising after he also claimed victory in Race Two at Phillip Island in the previous round and could perhaps have won all four races this season but for being run wide in the season opener.

Despite his maximum haul this weekend Spies is 10 points behind Haga at the top of the overall standings.

"In the first race we lacked a little bit of acceleration but I put my head down and was able to catch Noriyuki. He has set a really good pace," Spies said afterwards.

"The second race was better for me. I was just able to get my head down. I felt relaxed.

"It's hard though to make points up on Haga at the moment as he keeps finishing second."

Haga admitted it had been a tough day at the office, and is already feeling the pressure from his junior rival in Spies.

"I am very, very tired but I enjoyed the race," he said.

"I tried to push Ben but he is 10 years younger than me, maybe that is why I lost to him."