Beaten 1-0 at Feyenoord in their Group A opener, Jose Mourinho's side struggled to break down their unadventurous Ukrainian opponents until the introduction from the bench of Wayne Rooney.

The England captain's mishit shot was headed in by Ibrahimovic to leave United a point behind group leaders Fenerbahce, who visit Old Trafford on October 20.

It was a far from fluent performance, but it maintained United's upturn in form following the recent run of three straight defeats that had destroyed their early-season momentum.

Zorya, UEFA group-phase debutants, became United's 100th continental opponents and they threatened to create a sensation when Zeljko Ljubenovic ballooned over from Ivan Petriak's cut-back.

In the main, though, they sat back, packing men behind the ball in a 4-5-1 formation, and United struggled to play through them.

Ibrahimovic had a shot deflected wide by Dmytro Grechyshkin, but as in last Saturday's 4-1 win over league champions Leicester City, the hosts looked most threatening from corners in the first half.

With Daley Blind rested, Juan Mata took over set-piece duties.

From one of the Spaniard's deliveries, Paul Pogba flicked on and Marcus Rashford rattled a shot against the bar, the ball bouncing down a foot short of the line.

From another, Marouane Fellaini headed into the ground and over. In between, Mata headed over from a Pogba cross and Jesse Lingard saw a header blocked by Rafael Forster.

Just as he had in the first half, Ljubenovic set United's hearts fluttering early in the second when he narrowly failed to make contact with a cross from Olexandr Karavaev.

Indeed, it was the visitors who registered the match's first shot on target, with substitute Paulinho obliging United goalkeeper Sergio Romero to leap to his left and palm the ball behind.

Mourinho turned to Rooney, who had started on the bench for the second game running, and within two minutes the United captain had played a part -- albeit an unintentional one -- in the opening goal.

Released by Mata, Timothy-Fosu Mensah cut the ball back from the byline on the right to Rooney.

The United number 10 miscued his volley, directing the ball into the ground and away from goal, but Ibrahimovic rose at the back post to nod a close-range header over the line.

It was the Swede's sixth goal in 10 United appearances.

Rooney teed up Fellaini to volley wide from a corner and Ibrahimovic called visiting goalkeeper Oleksii Shevchenko into action with a late free-kick.

But the outcome would have been quite different had Paulinho not missed his kick from Mykyta Kamenyuka's cross at the other end.