The Newcastle Jets are keeping their heads up despite their relentless injury problems and a tough three-game A-League losing streak, midfielder Mateo Poljak says.Poljak is a strong contender to become Newcastles stand-in captain for at least the next few weeks after skipper Nigel Boogaard tore ankle ligaments in their 2-1 defeat to Melbourne City on Thursday.Its not yet clear how long Boogaard will be out for, but he was the player the Jets could least afford to lose following injuries to defenders Lachlan Jackson (ankle), Ben Kantarovski (knee) and Daniel Alessi (knee).Poljak, however, is staying positive, writing their injury curse off as bad luck and insisting the Jets are headed in the right direction.Its just unlucky. Fair enough if they were muscular injuries, youd think maybe somethings (gone) wrong, but its more impact and knocks, he told reporters on Tuesday.You cant really do much about it.It doesnt affect morale - obviously wed like to have more players, especially since the majority of them are starting players and leaders as well, but what do you do?I think weve got pretty good depth this year, well cover them.Former Adelaide United and Sydney FC centre-back Iain Fyfe has been training with the Jets since Monday and is likely to sign an injury replacement contract to act as cover for Boogaard, which would alleviate some of coach Mark Jones defensive headaches.Fyfe, now 34, has been playing in the South Australian NPL with Campbelltown City since 2014.I think the recruitment of Fyfey is quite a good thing for us, hes been vocal in the last couple of days, Poljak said.We have a strong leadership group but unfortunately a (because) couple of injuries, theres less and less experienced players.It does come up to a few of us to lead that and help young players and ourselves.The Jets take on Central Coast in the F3 Derby on Sunday at McDonald Jones Stadium.John Brooks USA Jersey . John Tavares, Thomas Vanek and Kyle Okposo were also being counted on to slow down sizzling Rangers forward Rick Nash. That plan didnt go so well early. Joe Corona USA Jersey . The No. 1-ranked Nadal tweaked his back warming up for the Australian Open final, which he lost almost four weeks ago in a major upset against Stanislas Wawrinka. His first stop after the layoff is the clay in Rio as he tests the back and tries to stay healthy for the French Open in three months. http://www.usasoccerauthority.com/geoff-cameron-usa-jersey/ . PAUL, Minn. Graham Zusi USA Jersey .J. -- Marty Brodeur beat the Pittsburgh Penguins yet again. Darlington Nagbe Jersey .5 seconds to play in the game, Kevin Love never stopped believing that they would come out of there with a win.NEW YORK -- A look at Mondays play in the $46.3 million U.S. Open tennis championships:WEATHER: Cool and cloudy early followed by mostly clear skies. High of 83.ATTENDANCE: Day: 36,728. Night: 24,932. Total: 61,660.MENS RESULTS (Fourth Round): No. 2 Andy Murray routed No. 22 Grigor Dimitrov, losing only five games; No. 3 Stan Wawrinka defeated Illya Marchenko in four sets; No. 6 Kei Nishikori beat No. 21 Ivo Karlovic in straight sets; and unseeded Juan Martin del Potro defeated No. 8 Dominic Thiem by retirement in the second set.WOMENS RESULTS (Fourth Round): No. 1 Serena Williams reached the U.S. Open quarterfinals for the 14th time, beating unseeded Yaroslava Shvedova in straight sets; unseeded Ana Konjuh upset No. 4 Agnieszka Radwanska in straight sets; No. 5 Simona Halep topped No. 11 Carla Suarez Navarro, also in straight sets; and No. 10 Karolina Pliskova outlasted two-time U.S. Open champion Venus Williams in three sets.TOP PLAYERRS ON COURT TUESDAY (Quarterfinals): Men: No.dddddddddddd 1 Novak Djokovic vs. No. 9 Jo-Wilfred Tsonga, No. 10 Gael Monfils vs. No. 24 Lucas Pouille. Women: No. 2 Angelique Kerber vs. No. 7 Roberta Vinci, Caroline Wozniacki vs. Anastasija Sevastova.STAT OF THE DAY: 308 -- Career Grand Slam victories for Serena Williams, passing Roger Federer for the most in the Open era.QUOTE OF THE DAY: Hopefully well both keep going. I know I plan on it. I know he does. So well see. -- Serena Williams, on whether she or Roger Federer will end up with more Grand Slam matches.TUESDAY ON TV (All Times EDT): Noon-11 p.m., ESPNON THIS DATE (Sept. 6, 1975): Manuel Orantes comes from two sets down and an 0-5 fourth-set deficit to beat Guillermo Vilas 4-6, 1-6, 6-2, 7-5, 6-4 and win mens singles title on clay courts at Forest Hills. ' ' '