The deadline arrived, but the announcement never did.

In a surreal ending to the transfer window in Spain, the much-anticipated move of Manchester United goalkeeper David de Gea to Real Madrid never materialized. The clubs reportedly struck a deal, but the expected announcement never came, apparently because the paperwork wasn't submitted on time.

Even before Serena Williams set foot in Arthur Ashe Stadium on Monday night, her path through the U.S. Open to complete a true Grand Slam became a lot easier thanks to losses by other top women.

And when it was the No. 1-seeded American's turn to play her first-round match, she was not tested one bit by a woman who appeared overwhelmed by the opponent, the occasion and, to make matters worse, an injured left foot.

Juventus have bolstered their depleted midfield following the departure of Andrea Pirlo and Arturo Vidal by signing Hernanes from Inter Milan and upcoming Frenchman Mario Lemina from Marseille.

Hernanes, known for his great ball control and play-making skills, signed a three-year deal worth 11m euros ($12.4million, £8million) to become Juve's second signing on the final day of the summer transfer period after France under-21 midfielder Lemina, who joins on a season-long loan deal.

Ex-Germany international and Bayern Munich captain Stefan Effenberg doubts veteran French winger Franck Ribery can return to fitness from the ankle injury which has sidelined him since March.

"If he comes back and manages to get 100 percent fit, then Bayern will need him," Sky expert Effenberg said of the 32-year-old Ribery.

Brazilian midfielder Casemiro has extended his contract with Real Madrid until 2021, the Spanish giants confirmed on Monday.

The 23-year-old has returned to the Santiago Bernabeu this season after a successful year at Porto as Madrid exercised a buy-back clause in the deal which took him to the Portuguese side.

Juventus goalkeeper Gianluigi Buffon has called on the stuttering Italian champions to stand up and be counted after a second consecutive league defeat left them in the Serie A Doldrums.

Juve won a fourth consecutive scudetto last season and secured their first league and Cup double in 20 years before ending a 12-year wait to challenge for the Champions League final last May.

Three-time defending champion Serena Williams begins her quest to complete a calendar-year Grand Slam while past winners Novak Djokovic and Rafael Nadal launch their campaigns Monday at the US Open.

World number one Williams has already captured the Australian and French Open and Wimbledon crowns this season and could be the first person since Steffi Graf in 1988 to capture all four major women's singles tennis crowns in the same year by hoisting the trophy at the end of the Flushing Meadows fortnight.

Russian third seed Maria Sharapova withdrew from the US Open on Sunday with a right leg injury, easing the path to a calendar-year Grand Slam for top-ranked Serena Williams.

US Open tournament director David Brewer announced Sharapova's exit, which allowed qualifying lucky loser Daria Kasatkina of Russia into the draw in Sharapova's place.

Ethiopian Mare Dibaba lived up to her billing as the world's fastest marathon runner by winning the grueling event at the world championships in a sprint finish on Sunday.

Dibaba timed 2hr 27min 35sec to edge Kenya's Helah Kiprop by just one second after a sprint in the final 50 meters of the race held in overcast, relatively cool conditions.

Usain Bolt has warned that people write him off at their peril after the imperious Jamaican sealed another world treble gold despite an injury-hit season.

Bolt anchored Jamaica to victory in the 4x100m relay to add to his wins in both the 100m and 200m, trumping his much-touted and controversial American rival Justin Gatlin.