Walker prodded the ball into his own net in the 22nd minute as the Spurs defender tried to deny United captain Wayne Rooney an easy scoring opportunity at a sunlit Old Trafford.
It was one of very few chances in a scrappy match, with Spurs’ hopes of an equalizer coming mainly in the closing minutes with two shots from attacking midfielder Christian Eriksen."It was a very difficult game because you have seen two teams that want to press, so every player at the ball had a very small (amount of) time to play,” Van Gaal told BT Sport. “We didn’t keep the ball too much ... but we created a few chances.”
As for his new signings, the Dutchman said: “It’s always difficult, it’s the first time they play at Old Trafford... but I Iiked the performance.”
Spurs coach Mauricio Pochettino made no secret of his feelings about the game’s turning point after 22 minutes.
“Very frustrated, disappointed, because until this moment we played much better, created some chances, we dominated the game,” he said. “And with one mistake, we give the opportunity to score.”
United started with four new players, with Sergio Romero in goal after Van Gaal decided that Real Madrid target David de Gea was not in the right frame of mind to play.
Fullback Matteo Darmain, along with midfielders Morgan Schneiderlin and Memphis Depay all made convincing debuts and Romero improved after some early signs of nerves.
Tottenham made by far the better start and could easily have been ahead after five minutes. Striker Harry Kane sent a clever chip over the United defense but Eriksen could only send his cushioned volley over the bar from close range with Romero at his mercy.
Spurs were repeatedly caught out by the offside rule as they tried to get behind United’s back four, but still looked the most likely team to score before gifting United its opener.
The visitors only had themselves to blame after a sloppy pass by Nabil Bentaleb gave the ball away in midfield. Ashley Young sped down the right flank before crossing for the unmarked Rooney, who had keeper Michel Vorm to beat. As the United striker hesitated, Walker arrived just in time to spear the ball away from Rooney’s feet, past a despairing Vorm and into the corner of the Spurs net.
The goal gave a United a lift and although there were no further scoring chances before the break, Van Gaal’s side began to move the ball around with more assurance.
Another of new United’s new signings, midfielder Bastian Schweinsteiger, replaced Michael Carrick on the hour mark of what was turning into a fairly scrappy encounter.
Tottenham waited until the final 10 minutes before pushing with any real conviction for an equalizer.
United defender Chris Smalling made a superb tackle to snuff out the danger from Nacer Chadli and Eriksen tried his luck with an angled drive that drew a good save from Romero.
Eriksen followed up by rifling in a powerful shot from outside the area in the 89th minute, but Romero was quick to make a block.
The final whistle came as a relief for United fans, who saw their club lose 2-1 at home to Swansea on the opening day last season.
“The most important thing today was the victory,” Rooney said. “After what happened last season, getting off to a bad start at home - we had a bad run of results after that - today was all about the three points. And we’ve gone out there and done that.”