Two members of the Force India team have decided to leave Bahrain, including one person who was in a team vehicle that was briefly delayed by a firebomb a day earlier.

The bomb exploded Wednesday night in Bahrain's capital Manama, causing a Force India van with four team members to be delayed in traffic on its way from the Bahrain Grand Prix circuit back to its hotel. No one in the vehicle was hurt and none of the four passengers were Formula One drivers, Force India spokesman Will Hings told The Associated Press by telephone from Manama on Thursday.

Lionel Messi and Cristiano Ronaldo's record goal-scoring form looms as the decisive factor when Spanish league leader Real Madrid plays at Barcelona on Saturday in a crucial "clasico" that will effectively determine the destiny of the title.

Madrid has seen a 10 point lead over three-time defending champion Barcelona whittled down to just four points over the past month, and a loss at the Camp Nou would see the advantage sliced to just one point with four more games remaining.

Paul Pierce's 29 points included a key jump shot with 7.6 seconds remaining as Boston beat Orlando 102-98 to clinch the NBA Atlantic Division title.

Pierce, who also handed out a career-high 14 assists, helped the Celtics overcome the absence of Rajon Rondo, who was still nursing a sore back after a spill in the defeat at New York on Tuesday.

London Olympic organizers said there is now a real buzz about the 2012 Games as they started the 100-day countdown on Wednesday by unveiling its 'Inspire a generation' motto.

The milestone was marked by events in Britain and around the world as London chiefs said they were looking in "great shape" before the sports extravaganza kicks off.

Didier Drogba scored the only goal as Chelsea stunned holders Barcelona to score a 1-0 upset victory in their Champions League semifinal first-leg match here on Wednesday.

Drogba left Chelsea dreaming of advancing to their first final since 2008 in next week's return leg at Camp Nou after pouncing on the stroke of half-time as Barcelona suffered their first European reverse of the season.

Athletic Bilbao are looking to continue their remarkable continental campaign and set up an all-Spanish Europa League final as they prepare to take on Sporting Lisbon in the semifinal first leg on Thursday.

Marcelo Bielsa's side have already beaten Paris Saint-Germain, Manchester United and Schalke 04 this season and the brand of football favored by the Argentine since his arrival at San Mames last summer has won admirers across Europe.

Seven-time defending champion Rafael Nadal and top-ranked Novak Djokovic got their clay-court seasons off to a good start with comfortable wins in the second round of the Monte Carlo Masters on Wednesday.

Djokovic opened with a 6-1, 6-4 win against Andreas Seppi of Italy and his archrival Nadal followed up by beating Jarkko Nieminen of Finland 6-4, 6-3.

Belgium's Kim Clijsters announced on Tuesday that she will bypass the clay season, including the French Open, in the hope of recovering from a hip injury in time for the grass season and the Olympic Games.

"The rehabilitation process following Kim's hip injury is going more slowly than expected," read a statement on the former world number one's website.

Tony Parker scored 29 points and added 13 assists to spark San Antonio past the Los Angeles Lakers 112-91, lifting the Spurs to the best record in the NBA's Western Conference.

Tim Duncan contributed 19 points while Argentina's Manu Ginobili added 15 as the Spurs won for the 18th time in their past 21 games, improving to 44-16 to edge past Oklahoma City, 44-17, for the top spot in the West.

Chelsea believe they can stymie the jaw-dropping goalscoring exploits of Lionel Messi and pull off an unlikely upset against Barcelona in the Champions League semifinals Wednesday.

Messi took his season's tally to an astonishing 63 goals in 52 games at the weekend with a double strike in Barcelona's win over Levante, leaving him just four shy of Gerd Muller's all-time single-season European record of 67.