A sizzling James Blake torched out-of-sorts world No.1 Lleyton Hewitt in devastating fashion to secure the United States the Hopman Cup tennis tournament in Perth.

The world No.28 Blake showed he has the total package using his destructive forehand to down the subdued Hewitt 6-3 6-4 in just over an hour.

He finished off an imposing American display after Serena Williams geared up for the upcoming Australian Open with a 6-2 6-3 win over a gallant Alicia Molik in 50 minutes.

But it was Hewitt's second loss in a row and it means he will head to Melbourne Park as a top seed without winning form.

It was the dreadlocked Blake's first win over Hewitt in five meetings and showed the part-time model was set to be a big hit in Melbourne.

The athletic Blake's forehand was running hot in the opening set against Hewitt taking it out 6-3 in just over half an hour.

Hewitt's frustration was evident with blood trickling from his knuckles after thumping his hand against his racquet strings in anger at himself.

But serving for the set Blake tightened up momentarily before surviving three break points to take it out.

The second set started disastrously for Hewitt losing the first four games before breaking Blake's serve for the first time to bring it to 4-2.

But just when there appeared to be hope Blake pounced again and served for the championship at 5-2 but netted a straightforward volley.

He dropped another two games before holding his nerve to finish off a memorable win for the American.

Williams flexed her sizeable muscles in her last hitout before the first grand slam event of the year at Melbourne Park against Molik.

She slammed down seven aces in the first set dropping just one point on serve against Molik, who hadn't dropped a set in the singles at the event before today.

The world No.94 Molik failed to find any rhythm against Williams, who dictated throughout registering 18 winners to four.

Molik didn't necessarily play that badly. She just ran into a red-hot Williams, who was finding her range in her fourth singles match of the Australian summer.

Williams said her decision to come out to Australia a week earlier than last time would help her quest for her fourth grand slam title in a row.

"I feel I am getting better and better I am glad I came over earlier this year," she said.

Williams also found time to praise Molik, who had a fine week with straight-set wins over No.17 Silvia Farina Elia, No.8 Daniela Hantuchova and No.37 Daja Bedanova.

"She's doing so well, it is good to see an Aussie coming up on the female's side, you already have one on the men's side so that is good," she said.

The Hopman Cup had records crowds for the week with more than 82,000 people attending.

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