Scott Parker was given a dizzyingly dramatic introduction as West Ham manager as the Hammers fought back from a three-goal half-time deficit to claim a chaotic 3-3 Championship draw at Cardiff City.

Only officially confirmed as Nuno Espirito Santo's successor on the morning of the game, Parker was given a stark illustration of the reasons for his recruitment as his new side fell apart with Jack Moylan's first-half hat-trick putting the hosts in charge.

Cardiff were as impressive as their opponents were dismal, Moylan spectacularly firing them into an early lead with a swerving 20-yard strike before scoring a penalty after drawing a clumsy foul from Morato.

The away fans were already chanting at their players "You're not fit to wear the shirt" by the time Moylan got a touch on Will Fish's flicked header from a corner to add Cardiff's third, which prompted furious boos from the away end.

At that stage, West Ham looked like sinking without trace, but Parker's half-time changes had a transformative effect, with Divine Mukasa's delicate chip and Arne Engels' first goal for the club reducing their deficit to just one goal with 25 minutes still left to play.

There could scarcely have been a sharper contrast between the first and second halves. Cardiff were ragged having dominated before the break, whereas West Ham were all over their opponents.

Such was the volume of Hammers pressure, there was an inevitability about their equaliser when Max Kilman volleyed in from a fine Jarrod Bowen cross, the captain's second assist of the night.

West Ham might even have snatched all three points were it not for some desperate Cardiff defending and saves from goalkeeper Nathan Trott.

As it was, a draw represented a remarkable turnaround and closed the gap on Championship leaders Middlesbrough to five points following their defeat at Wrexham.

Cardiff remain unbeaten at home this season but their second-half collapse keeps them 18th in the table.

There were barely 10 hours between the announcement of Parker's appointment and kick-off at Cardiff City Stadium. No time to ease himself in, for a job in which he has no margin for error.

Nuno was sacked a day earlier, paying the price for relegation from the Premier League last season and a frustrating start to this campaign – albeit not disastrous, the former Spurs and Wolves boss departing with the Hammers six points off the Championship summit.

Only promotion will do for West Ham and, in Parker, they have a manager who has accomplished that with three different clubs at this level.

He has inherited a squad still stacked with quality despite significant summer sales and, with 36 goals from 14 league games, it is easy to see why the former England midfielder was so keen to return to the club where he spent four productive years as a player.

It was equally clear, however, that Parker has many issues to address.

West Ham fell behind in the first half for the 11th time in 17 matches when Moylan fired in the opening goal, and their defending was passive and disjointed throughout the opening 45 minutes.

Parker can take encouragement from the Hammers' character to fight back after the break, knowing already how many technically gifted players he has at his disposal.

Given their resources and now with a proven Championship promotion winner at the helm, West Ham will expect to make an instant return to the Premier League this season – but they can ill afford to keep starting games on the back foot.

Cardiff head coach Brian Barry-Murphy:

"We're naturally disappointed that we didn't manage to win the game. I think it was the proverbial game of two halves from our point of view.

"We showed in the first half what we're capable of, and the players delivered an incredible performance.

"In the second half, we understood how difficult it may become, based on the quality of the opponents, and they just scored at moments of the second half that made it difficult for us to stem the flow. The players gave absolutely everything."

West Ham manager Scott Parker:

"The first-half performance was pretty poor. We had a really slow start. A lot of things didn't go well. We were very passive and slow with the ball.

"The biggest thing for me tonight is that there's a lot of learning that's taken place, particularly in terms of the team and the group. I came in here at nine o'clock this morning and met the players for the first time, so I didn't have a lot of input as such.

"The biggest positive is the team we saw in the second half. There were some changes based on what I was seeing in the first half, and the players adapted very well. We looked a real threat and dominant, and that's the team I want us to be."