On a scrap of paper at Selhurst Park last March, Jose Mourinho scribbled down the one word lacking from his Chelsea team after they had been beaten by Crystal Palace.

At Upton Park, Mourinho’s side showed ‘balls’ of steel, surviving a difficult game against one of those teams — and at one of those grounds — where anything can happen. Chelsea have the mentality of champions.

Their celebrations at Wembley on Sunday told a story, linking arms and sliding to their knees in front of their supporters after they had beaten Tottenham 2-0 in the Capital One Cup final.

Cesar Azpilicueta, John Terry and Ramires leave the Upton Park pitch after another victory for Chelsea

Jose Mourinho won the first trophy of his second stint at Chelsea and few would bet against him adding the title

Chelsea celebrate their Capital One Cup trophy win at Wembley and maintained their five-point lead

There have been markers at key stages of the season: a 2-0 win over Arsenal in October, 2-1 at Liverpool the following month and their stunning performance in the 5-0 win at Swansea in January.

This 1-0 victory at West Ham was another. Chelsea’s bond is strong, building this resilience in the dressing room as the season has progressed.

They looked impenetrable, especially in the closing stages as West Ham pushed for an equaliser. Their work-rate is phenomenal, a team fighting for each other as they close in on their first Barclays Premier League title since Mourinho returned to the club.

He described himself as a kid after he ambushed the trophy celebrations on Sunday, but it is on nights like this when the big boys go to work.

Look around the Chelsea dressing room and it will be difficult to separate some of these players when it comes to voting for the PFA Player of the Year in a few weeks’ time.

John Terry, exceptional against Tottenham at Wembley, must be in with a shout. Incredible as it sounds, he last won it in 2005.

Thibaut Courtois, returning in goal in place of Petr Cech, was exceptional. His first-half save from Diafra Sakho was top class. He oozes confidence, taking responsibility as the last line of defence after Terry’s early booking for a foul on Cheikhou Kouyate.

The doubts that crept in after a rare mistake in the 1-1 draw against Manchester City in January have been eradicated. Mourinho has made the right call to make him first choice.

Thibaut Courtois was again exceptional and could make it back-to-back titles after winning La Liga last year

Cesc Fabregas probes into West Ham territory with Enner Valencia and Mark Noble close by

Cesc Fabregas, what with those 15 assists in the league since his move last summer from Barcelona, will also be in the running.

Then there is last season’s Young Player of the Year Eden Hazard, the tormentor-in-chief down Chelsea’s left last night. He scored with a clever header from a cross by Ramires in the 22nd minute to secure his side’s 19th league victory of the season.

Sometimes he leaves you drooling. His composure on the ball, coupled with that ability to be able to run with it when he is looking at the options around him, are made to look like pure instinct.

Some of the twists and turns, creating space by leaving Carl Jenkinson and James Collins wrong-footed, were of the highest order. So what has changed since last season, when they gifted Manchester City their second Premier League title with a series of faltering performances?

They have the bottle for the big occasion now.

At Wembley last Sunday, Mourinho turned to a television camera and squirted water all over the lens after Terry had opened the scoring for Chelsea. Here they washed West Ham’s faces again.

Adrian dives in vain as Hazard's header sails past the Spanish keeper and into the back of West Ham's net

Hazard was in irresistible form and leads James Collins a merry dance here

For many different reasons, some tribal and some because of an irrational hatred of former player Frank Lampard, who has since left Stamford Bridge, away at West Ham is always a tough fixture for Chelsea.

To their credit they always seem to survive the taunts, the songs from the terraces that are usually directed at the captain Terry and his mother. Chelsea’s captain always appears unmoved by it all.

But there was more last night. When Kurt Zouma was fouled by Collins just before half-time, West Ham’s supporters sang ‘You won’t let him on the train’ when he was waiting for treatment.

Naturally those chants, given the dreadful incident on the Paris Metro before Chelsea’s Champions League clash at Parc des Princes last month, should be discouraged. Chelsea are the big noise in football right now, the team to beat as they prepare to face Paris Saint-Germain in the return leg of their last-16 Champions League tie next week.

Increasingly Chelsea look like a team determined to power on and finish the job in the Premier League after feeding off the scraps last season.

After this, the message from Mourinho was loud and clear.