After the break the Belgian doubled United's lead as he rose highest to head home a free-kick from Mkhitaryan. Manchester United have a few players out as well, with the knee injuries to Marcos Rojo and James Wilson still keeping them out long term, as well as long waits off the pitch left for Luke Shaw and Ashley Young.
Martial, who came on for the lively Rashford, passed the ball into the net for United's third goal in the 87th minute before Pogba wrapped up the scoring in the 90th minute.
Gary Neville is not buying into the notion that fourth is good enough for Manchester United this season. Yes it's only the first week of the season and yes it's too early to draw conclusions but United were hugely impressive here.
Andre Ayew nearly got the equalizer for West Ham United before the end of the first half when Hernandez supplied a great pass, but the Ghanaian star could not go past David De Gea. Both Manchester clubs won their opening three games last season and didn't win the league, but they'll both be a lot closer this season. From clever flicks to gorgeous passes with a couple of superb tackles in-between, Pogba was everywhere today.
The Belgium striker, a £75 million ($97.6 million, 82.5 million euros) signing from Everton, struck either side of half-time to take his tally of goals against West Ham to 11 in his last 11 appearances. Pogba looks like he could be about to make everyone eat their words this year. Mourinho expectedly gives the Old Trafford debut to Romelu Lukaku, spearheading an attacking lineup that includes fringe starters Marcus Rashford and Juan Mata.
Mark Noble captains the side, with Pedro Obiang also handed a start, while Andre Ayew and Marko Arnautovic will look to support Javier Hernandez on his return to Old Trafford.
Yet again, West Ham nearly shocked De Gea, when Masuaku floated in a left-wing cross that Arnautović headed over the Spaniard onto the top of the crossbar and, after Antonio Valencia was cautioned for a lunge on the Austrian, Bilić made a double-switch with Diafra Sakho and young Declan Rice replacing Fernandes and the dejected Noble.
Mattis says U.S. wants diplomatic solution for NK
Trump said North Korean leader Kim Jong Un was not going to get away with his "horrific" comments and disrespecting America. Trump has said he would not allow Pyongyang to develop a nuclear weapon capable of hitting the United States.
Indian Squad announced for Sri Lanka ODIs and T20I
Left-arm spinner Axar returns to the Indian team for the first time since October 2016, when he played the last of his 30 ODIs. Among others, those who have missed the cut are Rishabh Pant, Dinesh Karthik, Ravindra Jadeja and Ravichandran Ashwin.