Soccer-Penalties decide three semi-finalists at U-20 World Cup

* Brazil through on penalties for second straight match * Portugal rue several missed chances * Mali surprise Germany in shootout (Updates after later games) By Greg Stutchbury WELLINGTON, June 14 (Reuters) - The pressure of knockout soccer reared its head at the under-20 World Cup in New Zealand on Sunday with three of the four quarter-finals decided by penalty shootouts. Brazil, Mali and Serbia all advanced to the semi-finals courtesy of nerve-shredding shootouts, as heavyweights Portugal, Germany and the United States all crashed out. Only Senegal sealed a result inside the 90 minutes following a 1-0 win over Uzbekistan in Wellington. It was the second successive match the Brazilians had won on penalties as they held their nerve to win 3-1 after they were lucky to escape with a tense 0-0 result against Portugal after extra time. Mali and strong favourites Germany had been locked at 1-1 after extra time before the African side prevailed 4-3 on spotkicks, while Serbia won 6-5 after their match against the U.S ended in a scoreless stalemate. Brazil had beaten Uruguay 5-4 on penalties in the round of 16 and coped with the pressure better than the Portuguese, who saw Raphael Guzzo, Andre Silva and Nuno Santos all miss from the spot in Hamilton. Portugal wasted numerous chances to seal the game in normal time, with Rony Lopes coming closest with a snap-shot on the turn that slammed off the far post. Lopes also wasted a gilt-edged opportunity in the first spell of extra time when he was put through one-on-one with Brazil goalkeeper Jean, but he pushed his shot wide of the post. The normally ice-cool Germans also appeared to have suffered an attack of nerves and went out after Julian Brandt and Niklas Stark missed their spot kicks in Christchurch. Germany were seemingly coasting to the semi-finals after Brandt opened the scoring in the 38th minute as Frank Wormuth's side dominated possession. A missed 56th minute penalty by Hany Muklhtar, however, proved to be a portent of what was to come as Mali goalkeeper Djigui Diarra's diving stop gave confidence to his team mates with Souleymane Coulibaly equalising two minutes later. Senegal joined their west African counterparts in the last four after Mamadou Thiam scored the only goal that sealed a result in normal time when he slotted home from a Remi Nassalan jinking run in the 77th minute. Joseph Koto's side had looked the far better of the two teams, putting Dilshod Khamraev under immense pressure throughout with the Uzbek keeper forced to make two world class diving saves to keep his team in the game. In Auckland, Nemanja Maksimovic, the ninth Serbian to take a spot kick, finally sealed the shootout when he beat Zac Steffen to set up a semi-final with Mali at the same venue on Wednesday. Neither side were able to finish off the shootout, with Steffen and his Serbian counterpart Pedrag Rajkovic making two saves each, while both sides combined to miss three other shots, only increasing the tension for both sides. Brazil will play Senegal in Christchurch in the first semi-final on Wednesday. (Reporting by Greg Stutchbury; Editing by Peter Rutherford/Sudipto Ganguly)