Novak Djokovic of Serbia hits a return to Andreas Seppi of Italy during their men's singles quarter-final match at the ATP Dubai Tennis Championships, February 28, 2013.  [Photo/Agencies]

DUBAI - Novak Djokovic and Roger Federer stayed on course for a scorching desert showdown as they led the top four seeds into the semi-finals of the Dubai Championships on Thursday.

The world's leading two players were joined in the last four by Czech Tomas Berdych and Juan Martin Del Potro of Argentina.

Djokovic extended his winning streak to 16 matches as he routed Andreas Seppi 6-0 6-3 to set up a 10th meeting with Del Potro, whose thunderous serving helped him overwhelm German qualifier Daniel Brands 6-4 6-2.

Federer vanquished Russia's Nikolay Davydenko 6-2 6-2 and world number six Berdych swatted aside wildcard Dmitry Tursunov 6-3 6-2.

Federer and Djokovic, winners of eight of the past 10 Dubai finals between them, have topped the bill each night, while the lower seeds have played in the blistering afternoon heat and that could leave the top two in better condition for Friday's semi-finals.

Djokovic has a 7-2 winning record against Del Potro and has been victorious in their last three matches, but the Argentine did beat Djokovic to claim an Olympic bronze in London last year.

"Del Potro is a fantastic player, he's very powerful and has a great serve," Djokovic said in a courtside interview. "He likes this court, plays very aggressive, so I'll have to be on top of my game."

The Serb had been lax in the closing stages of his second- round match and he began Thursday in a similar fashion, perhaps complacent due to a 9-0 winning record against Italian Seppi.

Djokovic's first serve was rarely on target in the opening game and a netted forehand left him facing a break point, but the 25-year-old escaped with a venomous serve and eventually held.

That scare seemed to refocus the Serb, who broke immediately by exposing Seppi's limitations - an erratic serve, short returns and a limp backhand.

The Italian won just 11 points in a first set whitewash and Djokovic broke decisively for a 3-1 second set lead as a flat-footed Seppi played a forehand that did not even trouble the tram lines.

Del Portro Confident

Earlier, Del Potro was bullish after a relative stroll against the big-serving Brands.

"If I am ready and I'm very solid with my forehands and serve  it's going to be a very big chance for me," Del Potro told reporters.

That confidence is a reflection of the former U.S. Open champion's improving form in Dubai following a scare in the first round in which he saved three match points before beating Marcos Baghdatis. He has not lost his serve since.

Cheered on by pockets of Argentine support decked out in the blue and white stripes of the country's football team, he conceded just 10 points on serve against Brands in the volcanic afternoon heat.

Federer, 31, dismantled Davydenko to claim a 19th victory in 21 against the Russian.

The Swiss broke with ease, on the second occasion dragging the Russian out wide with an angled drive the despairing veteran could only arc long.