Ange Postecoglou told Leigh Griffiths he has to work to win back the Celtic fans after he was booed by a section of them in the 6-2 friendly defeat to West Ham at Parkhead.

The Hoops boss made 10 substitutions in one go in the second half and 30-year-old striker Griffiths, recently cleared by police over allegations of sending inappropriate messages to two schoolgirls, elicited a negative reaction.

Police Scotland said it had established "no criminality" after carrying out a "full assessment" on claims Griffiths exchanged improper messages with a 15-year-old girl as well as another teen girl on social media.

Some supporters then got behind the forward, who recently signed a new one-year extension with the Parkhead club, and he caused a stir in the stands every time he got on the ball.

Asked if he was confident the Scotland international can win over the fans, boss Postecoglou said: "That's going to be down to Leigh and his performances.

"If he works hard at training and produces the kind of football he can, scoring goals, I'm sure the crowd will get behind him.

"I won't be telling the Celtic supporters anything. They've followed this club a lot longer than I've been here.

"My job is to produce a team they're proud of and we let them down today.

"Maybe it is a big challenge for him but that's what he wanted. He had a choice, he didn't have to come back. He wanted to come back and play for the club again. He wanted to contribute.

"When you make that decision, you embrace everything that comes along with it."

It was a chastening afternoon for Celtic ahead of the second leg of their Champions League qualifier against Midtjylland on Wednesday, following Tuesday's 1-1 draw at Parkhead.

Hoops skipper Callum McGregor curled in the opener in the seventh minute before Hammers striker Michail Antonio scored a quick-fire double and captain Mark Noble netted from the penalty spot.

Ryan Christie pulled a goal back five minutes after the break but goals from Said Benrahma, Jarrod Bowen and substitute Armstrong Okoflex, signed from Celtic this summer, added to the scoreline.

The former Australia manager, who revealed missing striker Albian Ajeti "had a little knock" and midfielder Olivier Ntcham "just wasn't ready", was candid about the defeat but still believes Celtic can go through against the Danes.

He said: "It was disappointing because there were some positive things in it. But there were also bits of our game that were poor.

"And against a good quality opponent you get punished. Collectively, we didn't stick to our task in a defensive sense.

"We were bright going forward and showed a willingness to play our football. But you've got to match that with the other side of the game.

"This result makes no difference to my confidence ahead of Wednesday. We knew it was going to be a tough challenge going over there.

"We saw in the first leg that we played well but it was still a tight contest. It will be the same in the second leg."

West Ham boss David Moyes, a former Celtic defender, was pleased to see Antonio get on the scoresheet.

He said: "Michail hadn't scored in a couple of games and I think he was a bit worried about it.

"He was through on the goalkeeper right at the start and should probably have got at least another one."

Moyes also warned 19-year-old Irish winger Okoflex not to get too carried away with his goal against his former club.

He said: "It was (nice) but he has a lot to do. If I was him I wouldn't get carried away with that goal.

"He still has a lot to get done and hopefully improve if he is going to be a regular around the first team at the moment."