So before Jose Mourinho's Premiership leaders step onto the Camp Nou in Barcelona tonight, they'd do well to heed the advice of their greatest ever goal-scorer. Thirty nine years ago, Chelsea were also pushing for a league title, and Bobby Tambling was a key member of their side.
Tambling scored 202 goals for the Blues between 1958 and 1970 a record that remains. Older Blues fans still rate Tambling as one of the club's all-time greats.
Now living in Crosshaven in Co Cork, Tambling has painful memories of playing in the Nou Camp against the Catalans, also on the back of a bitter FA Cup exit.
"We played them in the Fairs (UEFA) Cup semi-final in 1966," recalls Tambling. "We lost 2-0 at the Nou Camp but then beat them 2-0 at our place. In those days there was no extra-time in the competition. A coin was tossed to decide where a third match would be played. We lost the toss and had to play in Spain again.
"The weekend before we went out for the third game we had just been beaten in the FA Cup semi-final. We were low in confidence and they thumped us 5-0."
Tambling, a League of Ireland winner with Cork Celtic in 1974, warns the present Chelsea side must not be intimidated if they are to avoid a similar FA Cup hangover.
"Even though all this Chelsea side are internationals, Barcelona is still a very daunting place. They have got to go over there with confidence although I'm sure the manager will have the players up for this game."
Nevertheless, Tambling, a star at inside-forward, admits doubts over Chelsea's current striking options. "Didier Drogba is a good player but he still has to prove he is world class.
"Gudjohnsen has done well to get a couple of goals and seems to be preferred by the manager but with Robben already injured, you'd be very worried with Duff also now out.
"I still don't think this Chelsea side will concede many goals. Barcelona might not have the kind of Chelsea style to grind out results. They don't often win 1-0 and this is going to be much tighter than they're used to. I'd still fancy Chelsea for the tie."
It's hard to believe the Russian money machine dominating west London is the same club Tambling joined as a 15-year-old in 1957. While Chelsea's stars of 2005 earn up to £100,000 per week Tambling's rewards were more modest.
"A couple of weeks ago, my family actually found my first professional contract which I signed in 1958. I got £10 per week during the season and £8 a week in the off-season.
"Even the best players at the club then would only get £20 a week. There was no such thing as agents. If you were looking for a new contract, you'd go into the manager's office with a couple of notes of what you were looking for scribbled on the back of a cigarette box."
While Chelsea 2005 have the mighty Mourinho, the Swinging Sixties Chelsea had the dictatorial Doc. "It's very hard to compare Mourinho with Tommy Docherty," laughs Tambling. "Docherty wasn't very aware tactically. He would annoy players so much, they would play well to show how much they hated him."
Docherty's other motivational method was more to Mourinho's liking. "He'd keep telling players they were world-beaters, even when they weren't."
Tambling believes the cocky Portuguese has something extra, however. "All the players want to win for him. I met John Terry and Damien Duff at Stamford Bridge and they spoke of how they adored Claudio Ranieri. It seems they want to play for Mourinho even more. He has brought this loyalty to another level."
This loyalty is all the more amazing when you consider the nationalities of the players another big change at the Bridge. "It seems funny now but we used to think a Scot and a Welsh lad or and Irish lad were a lot of foreigners in a team," says Tambling, now active in coaching at Crosshaven.
"I would prefer if there were more local lads in the team. It's good that John Terry is there. I think it's important youth is given a chance.
"When I was at Chelsea, the manager felt if young players had talent, they were given the chance. I know fans want to win the league no matter who the players are, but they'd prefer if it was with lads from their own area.
"Some young players won't get the chance at the big clubs. And it's bound to effect the national teams. Look at Scotland: the top teams are dominated by foreign players. Scotland used to produce players with an awful lot of talent. Now, I couldn't name three Scottish internationals."
Times change, and utterly at Stamford Bridge since Tambling played for the Blues alongside the likes of Terry Venables, David Webb and Ron Harris in the great Chelsea sides of the 1960s a side that almost ended Chelsea's championship thirst.
The swagger of 1960s side is back in the Chelsea step. Like all fans, he is excited. As Chelsea approaches its centenary, the days of being the almost club could be over. Almost.
THE Chelsea side Bobby Tambling starred with was one of the great sides of the 1960s, yet their self-destruction meant they had just a 1965 League Cup win to show for the decade.
Tambling, from Hayling Island, near Portsmouth, joined Chelsea in 1957 and soon found himself pushing for the first team at Stamford Bridge.
In the early days he played alongside Jimmy Greaves, while as a young player he grew up and blossomed alongside a bold young generation including Terry Venables, George Graham, Ron 'Chopper' Harris, Peter Bonetti and David Webb.
With this talented group, the club seemed destined to add to their sole league title of 1955.
The squad was torn apart before its time, however, sparked by a 1965 bust-up between then boss Tommy Docherty and eight players who broke a pre-match curfew with two games left in the season and Chelsea just two points behind Manchester United.
Headstrong captain Terry Venables led the revolt. "Docherty felt let down, and he had lost the trust of the players.
"Within a year and a half, players like Barry Bridges, George Graham and Terry Venables had moved on. Eddie McCreadie said he could never feel the same way for the club. We were still getting better. Nearly all these players were under 23 and the side was never really allowed reach its peak."
Tambling made three appearances for England, scoring against France, and was in Alf Ramsey's training squad for the 1966 World Cup.
"I had a decent run of form coming into the end of the season, and was in with a chance on the back of that," recalls Tambling. "I remember Geoff Hurst was something similar but his form carried on at the training squad. Everything he touched went into the goal.
"A lot of the press in England at the time thought it was a bit of a surprise I didn't make it but I wasn't overly surprised. I didn't think I did enough really to be in the squad."
Tambling continued as a stalwart for Chelsea, and eventually left in 1970 after losing his place in the side through injury, only to fail to get it back in a historic season for the club.
"I was gutted at missing the FA Cup final in 1970, because I'd already lost in an FA Cup final and in semi-finals."
The time to leave his beloved Chelsea arrived, and he moved across London to Crystal Palace. Injuries were now taking their toll and he was advised to quit the game.
"The doctor told me I couldn't play on hard ground, that I could only play on softer pitches. An Irish lad with Palace at the time, Paddy Mulligan, said I should play in Ireland because the pitches were always much softer.
"It started as a joke but Paddy actually did an awful lot of work to help me move to Ireland."
Tambling won a league title with Cork Celtic in 1974 a win that gave him a chance to play in the European Cup after years of trying with Chelsea.
He is still fondly remembered at Chelsea, and last year, as the Abramovich regime tightened its grip on Stamford Bridge, the club honoured Tambling by naming a suite after him at Stamford Bridge.
The thought of returning there to celebrate a Premiership title brings a wry smile to his face.