Borussia Dortmund's CEO Hans-Joachim Watzke insists his side are not capable of ending Bayern Munich's domination over the course of a Bundesliga season, ahead of Sunday's top-of-the-table clash.

German league leaders Bayern host second-placed Dortmund at Munich's Allianz Arena with Borussia four points behind Pep Guardiola's Bavarians, who have won all seven league games so far this season.

Cristiano Ronaldo refused to commit his future to Real Madrid just hours after becoming the club's joint leading scorer of all time with two goals on Wednesday.

Ronaldo equaled Raul's record of 323 goals for the Spanish giants in their 2-0 Champions League win over Malmo despite Raul playing over 400 games more for Los Blancos than the Portuguese star, who also passed 500 career goals on the night.

Former world champion Jenson Button is to stay on at McLaren for next season, ending speculation that he was about to retire from Formula One racing.

"McLaren-Honda is happy to confirm that Jenson Button will race for the team in 2016," team chief Ron Dennis announced.

World number one Serena Williams announced Thursday her withdrawal from next week's China Open in Beijing and the WTA Finals in Singapore, ending her season.

"I am taking a proactive step and withdrawing from tournaments in Beijing and Singapore to properly address my health and take the time to heal," the 21- time Grand Slam winner said in a statement.

Two goals from fullback Filip Mladenovic powered Belarusian underdog BATE Borisov to a surprise 3-2 win over Roma in the Champions League on Tuesday.

BATE was three goals up after 30 minutes, helped by a dose of good fortune in the Group E match.

Maicon scored the winner as FC Porto beat Chelsea 2-1 in the Champions League on Tuesday and heaped more misery on Jose Mourinho's team.

Yacine Brahimi helped put Porto ahead in the 39th minute when he beat Branislav Ivanovic on the left, and goalkeeper Asmir Begovic could only push away his shot as far as Andre Andre, who volleyed into the net.

A goalkeeping blunder by David Ospina helped Olympiakos beat Arsenal 3-2 in the Champions League on Tuesday and leave the Gunners in real danger of its first group-stage exit in 16 years.

Ospina fumbled a corner over his line to give the visitors a 2-1 first-half lead, and substitute Alfred Finnbogason scored the winner in the 66th minute — almost immediately after Alexis Sanchez had drawn Arsenal level.

Barcelona midfielder Andres Iniesta has hurt a leg muscle and will join Lionel Messi on the European champion's injured list.

Iniesta asked to be replaced in the 60th minute of Barcelona's 2-1 comeback win over Bayer Leverkusen in the Champions League on Tuesday.

French driver Romain Grosjean, winless in five Formula One seasons, was named Tuesday as the new driver for the Haas F1 Team that will enter the series next year.

The first American-led F1 entry in 30 years has an experienced driver as 29-year-old Grosjean, with 10 podiums in 78 F1 races, announced his departure from the financially struggling Lotus squad at the team's North Carolina headquarters.

Manchester United manager Louis van Gaal has hinted he could stay on at Old Trafford beyond his current contract.

The Dutchman has previously stated that he will retire from football when his deal with United expires in 2017 to spend more time with his wife Truus at their villa in Portugal.