Frank Lampard believes Patrick Bamford should be "proud" of how his career has progressed since leaving Chelsea as Lampard plans to nullify the former Blues forward on Saturday.
Leeds travel to Stamford Bridge to take on Chelsea on Saturday - live on Sky Sports - with Bamford, who has scored seven league goals already this season, expected to lead the line for the visitors.
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Lampard was still a key part of Chelsea's midfield when Bamford joined the club as a teenager from Nottingham Forest in 2012, while he spent a year playing alongside Jack Harrison during the pair's time with New York City in 2016.
Bamford never made a first-team appearance for Chelsea but was a key part of Leeds' promotion back to the Premier League, as well as stepping up this campaign, while Harrison has the joint-highest number of league assists for Bielsa's side.
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"I remember him well," Lampard said of Bamford. "He was a young player when he arrived at the club. Clearly he had great finishing abilities and an eye for goal.
"Obviously it didn't quite work out for him - that's probably more due to the competition he faced during that period up front for us.
"I think he should be proud of the way his career has gone; to make different moves and come back and be one of the leading scorers in the Premier League, in a very good Leeds team.
"Jack is a million miles from the player he was in New York. I hope that doesn't sound negative in any way because he was a real developing player at that point.
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"An absolutely lovely lad - I've got so much time for Jack. We keep in touch and I actually spoke to him the other day.
"The player that he has developed into at Leeds has been really, really impressive."
'It's in the past' - Lampard puts spygate behind him
Lampard was highly critical of Marcelo Bielsa during the "spygate" saga two seasons ago when the former England midfielder was in charge at Derby.
Bielsa sent a staff member to spy on a Derby training session, later admitting he had spied on every club he had faced, while the Rams beat Leeds in an acrimonious Sky Bet Championship play-off semi-final later that season.
Lampard reacted furiously while Bielsa was fined £200,000 by the Football Association, but the Blues boss has played down any bad blood between the pair.
"It's in the past," Lampard said. "I'm certainly not going to dwell on it going into this game. I'd rather dwell on the respect I have for him as a coach.
"It was a great news story, it had a lot to it. It's gone. I just look at how well he did - he brought Leeds up the year after.
"They were probably the strongest in the Championship the year that we played against them at Derby. It was a very proud moment for myself to go against him and win that game, but it's a game long gone.
"I'm not concerned about what lesson he's learned or not. I respect him, I respect Leeds. I'm only concerned with us being right tomorrow to try to win the match."
Leeds' visit will be the first time Chelsea have faced their old rivals in the top flight in 16 years and Lampard is wary of the threat they can pose to his side, who have more clean sheets than any team in the Premier League this season.
"I think it will be a big test for us," said Lampard. "If you analyse Leeds - not an easy team to analyse because of the way they play - lots of shots, scoring goals against top teams, pretty much against anyone they create a lot.
"So we'll have to be at our absolute best in terms of concentration and togetherness as we defend. We've been showing some really good signs - that's how you get clean sheets.
"It will be a huge test against Leeds because they're one of the most dangerous teams in the league."