Raonic, Berdych advance to last 16 at ATP Paris Masters.

Fourth seed Milos Raonic hit 17 aces here on Tuesday to beat Pablo Carreno Busta 7-6 (5), 6-4 for a berth into the last 16 of ATP Paris Masters.

The 25-year-old Canadian, who received a bye into the second-round contest, took one hour and 14 minutes to see off the world No. 31 Spaniard, also 25, without facing a single break point.

After pulling out of the China Open semifinals with a right ankle injury, losing in the third round of the Shanghai Masters and last week's Swiss Indoors first round, Raonic is hoping to use the Paris tourney to fine tune his preparation for the ATP World Tour Finals.

"I need to go flat out because I have struggled, I think, now for the better part of a couple months," said the big-server.

"There is no working your way into it come two weeks. You got to play against the top players right away from the beginning, so it is about really putting in those gritty moments here to lead into that," he added.

Earlier on Tuesday, Tomas Berdych kept alive his hopes of qualifying for the season-ending finale in London with a tight win over Joao Sousa.

The seventh-seeded Czech, who slipped below Marin Cilic in the race to 02 after the Croatian won at Basel last week, rallied past the Portuguese 6-3, 3-6, 7-5, although Sousa had two break points at 4-4 in the deciding set.

Later, Frenchman Richard Gasquet lifted the home crowd when he saw off American Steve Johnson 6-4 7-6 (11), before 14th seed Grigor Dimitrov progressed after Marcos Baghdatis retired at the start of the second set, having lost the first 6-3.

Also on the day, Gilles Muller of Luxembourg came through 6-3, 6-3 against Spain's Nicolas Almagro to set up a rendezvous with the top-seeded Novak Djokovic in the second round.

American John Isner beat in-form German Mischa Zverev 7-6 (8), 6-4 to move beyond the first round, while Nicolas Mahut of France needed three sets to defeat Martin Klizan of Slovakia 4-6, 6-4, 6-3.

Serbia's Viktor Troicki beat French wildcard Adrian Mannarino 6-4, 3-6, 7-6 (5) to set up a second-round tie against fifth seed Kei Nishikori, while Jack Sock of the United States beat German Philipp Kohlschreiber 6-2, 7-6 (3).

Spaniard Feliciano Lopez recorded a 7-6 (3), 6-4 win over French qualifier Pierre-Hugues Herbert and Ivo Karlovic of Croatia beat Serbian Dusan Lajovic 7-6 (4), 7-6 (5). Endit