West Ham United put their relegation worries to one side to reach the quarter-finals of the FA Cup for the first time in 10 years by defeating London rivals Brentford 5-3 on penalties.

Dango Ouattara was guilty of a terrible miss while attempting a Panenka before Konstantinos Mavropanos struck the winning kick to book the Hammers a last-eight home tie with Leeds United.

In a dramatic game, Jarrod Bowen's 19th-minute close-range finish - after Brentford failed to deal properly with a corner - put the Hammers ahead before Igor Thiago equalised eight minutes later with his 20th goal of the season.

Captain Bowen restored West Ham's lead by sending Caoimhin Kelleher the wrong way from the penalty spot in the 34th minute following Michael Kayode's foul on Adama Traore.

It looked like the Hammers were closing in on victory until in-form Brazilian forward Thiago forced extra time from the spot after Crysencio Summerville's 80th-minute foul on Kayode.

There were no further goals in extra time, with Kelleher producing an outstanding one-handed save to keep out substitute Callum Wilson.

But West Ham, coupled with Ouattara's poor attempt, held their nerve during the spot-kicks to go through.

Will West Ham use this win as a springboard in their battle to stay in the Premier League?

With a home match to come against title-chasing Manchester City on Saturday, the Hammers made seven changes - yet it was a trusted and familiar face who helped send them through.

Bowen has served West Ham tremendously during his six years at the club and the England attacker will be required to play a huge part over the next few weeks if his side are to avoid relegation.

Eighteenth - level on 28 points with 17th-placed Nottingham Forest - West Ham have nine league games to save themselves.

But this latest win, after last week's crucial victory at Fulham, suggests they are on an upward trajectory compared to Tottenham, who sit just two places and one point above them in the table.

This season has been littered with low moments like the 5-1 home defeat by Chelsea back in August and the 3-0 surrender at rock-bottom Wolves in January.

Yet a campaign that started with Graham Potter at the helm could astonishingly end with a Wembley appearance.

Beat Leeds in the sixth round and West Ham can look forward to a day out at the national stadium in the semi-finals of a competition they last won in 1980.

Brentford have never advanced further than the quarter-finals in the FA Cup - and their run in this season's competition ends at the fifth-round stage.

Thanks to a highly impressive first season in charge by Keith Andrews, the Bees are daring to dream about playing in Europe.

It has been a campaign of highs in the Premier League, yet there will be disappointment among their 5,500 away following at London Stadium that they were unable to overcome a West Ham side that has struggled all season.

Andrews' starting line-up - and the involvement of Thiago and Schade - suggested he saw this as a great opportunity to go deep in the FA Cup.

Brentford showed great character to twice come from behind to force extra time, while they will feel aggrieved they were not awarded a penalty after Mateus Fernandes' foul on Schade towards the end of the first half.

But former Bournemouth winger Ouattara will be haunted by his miss in the shootout.

With West Ham leading 2-1 on penalties, he took an age before stepping up to take his kick - and hit a tame effort straight at Alphonse Areola much to the delight of the home fans.

West Ham host title-chasing Manchester City at London Stadium on Saturday (20:00 GMT), while Brentford have a full week to prepare for their Premier League home game with bottom side Wolves next Monday (20:00).