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World number two Simona Halep, sixth-seed Angelique Kerber and two time champion Venus Williams tumbled out of the US Open as upsets wreaked havoc on the women's field. French Open champion Maria Sharapova was trying to avoid the upset bug when she took the court against Sabine Lisicki for the night's final match on Friday. Instead the fifth-seeded Russian was hoping to match the smooth progress of men's second seed Roger Federer, who found a way past the booming serve of Sam Groth in a 6-4, 6-4, 6-4 second round victory over the 104th-ranked Australian. "You don't get much time to adjust," said Federer, who returned one 142 mph (228.53 Km/h) Groth serve for a winner.
Britain raised its terror alert level Friday over fears of possible jihadist attacks as the United Nations said the number of refugees from the Syria conflict now tops three million. British Prime Minister David Cameron told reporters there was "no doubt in my mind" that jihadists from the Islamic State (IS) group in Iraq and Syria had their sights set on targets in Europe. Despite the move, White House spokesman Josh Earnest said Washington had no plans to follow suit, but US national security officials had been in close contact with London on the issue. US President Barack Obama has admitted that he has no immediate strategy to tackle advancing IS jihadists.