FROM STAMFORD BRIDGE - The feel-good factor that was beginning to bubble at Chelsea this summer was burst by a shock home defeat to Nottingham Forest on Saturday.

After scrapping back to earn a deserved draw against Liverpool on the opening weekend of the Premier League season, the Mauricio Pochettino era came crashing back to Earth with a humbling loss at West Ham United.

A sizeable win versus Luton Town was followed by an unconvincing one with a much-changed side against AFC Wimbledon in the Carabao Cup. The transfer window closed with the squad still simultaneously bloated on the whole and lacking in key areas.

In order to head into the international break without a minor meltdown, Chelsea needed to beat Forest. They did not.

The Blues were quick out of the blocks and Raheem Sterling was denied a first-minute opener thanks to a last-ditch tackle from Cobham graduate Ola Aina. That would be the closest they came to scoring in the first half as Pochettino's men failed to sustain attacks and break Forest down.

They were duly punished on the other side of half-time. The dawdling and wandering Moises Caicedo was pickpocketed of the ball by Orel Mangala and Ryan Yates, with the loose ball forwarded by Taiwo Awoniyi into the path of Anthony Elanga to calmly slot past Robert Sanchez.

Pochettino threw on three attackers - Noni Madueke, Mykhailo Mudryk and debutant Cole Palmer - but none were able to influence proceedings, partly due to their youth and inexperience, partly due to Forest's robust deep block.

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Chelsea's only fit number nine, Nicolas Jackson, squandered the best chance to level, poking Sterling's cutback over the bar from a few yards out.

The young Blues were unable to keep their heads and constantly found themselves running down dead ends, with the loss hardly one they could feel hard done by.

Pochettino is one of the world's best coaches when guiding a young up-and-coming team. It's his forte. This is a unique challenge that he has never encountered before, however.

The average age of Chelsea's squad is now just 22.5. Among only their 12 summer signings, it's 20.5. A regular club could stomach a few losses here and there and focus on the process, but Chelsea are an institution that bring different sorts of pressure.

Todd Boehly and BlueCo waltzed into Stamford Bridge last summer and ripped up a winning blueprint that didn't need ripping up. The decision to move away from the battle for constant success to a vision more long-term than any other in perhaps the history of English football was baffling even at the time it began.

They have now spent over £1bn on primarily young players, including several prospects with a view to sending them to a new sister club in Ligue 1 side Strasbourg. Chelsea finished 12th last season, their worst return since 1993/94, and their new setup with Pochettino is already crumbling under the remaining pressures.

Pochettino and Chelsea need time to iron out the kinks and shave down the faults of the league's youngest team, but they carry the weight of expectation of one of the sport's most important clubs. Saturday saw them fall to a simple defeat, but it's a glaring warning to those upstairs - their plan remains doomed to fail on this trajectory.

What will help Chelsea is that Pochettino is a coach that will make them fitter and stronger, tougher to beat as the season goes on - this will be particularly helped by their lack of European competition compared to their rivals. The building blocks are there for the team to be good, but not for the club to be great.

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This article was originally published on 90min as Chelsea stuck with paradoxical need for patience after spending £1bn on transfers.