The Blues recorded their fifth straight top-flight victory to move up to third in the table, with Tammy Abraham and Christian Pulisic scoring in either half.
Yet they endured some nervy moments in the closing stages due to Gerard Deulofeu’s 80th-minute penalty, which was only awarded following a VAR check after referee Anthony Taylor had initially ignored the Hornets’ appeals.
The VAR review deemed Jorginho had tripped Deulofeu, but the contact looked minimal and he appeared to take another step before going to ground.
Chelsea held on – though Kepa Arrizabalaga needed to make a brilliant last-gasp stop from fellow goalkeeper Ben Foster’s header when the stopper came up for a free-kick – yet Lampard was angry that Watford were handed a route back into the match with their penalty.
“I have to be careful really but last week we saw a change in VAR, a clear change in penalties getting overturned,” Lampard told reporters at his post-match news conference.
“I was at a managers’ meeting in midweek and we spoke a lot about it.
“The absolute consensus from managers, referees, the Premier League was the penalties or decisions — this is what I took from the meeting, anyway — are not going to get overturned unless they’re absolutely clear and obvious, and the VAR absolutely saw something that the referee on the pitch didn’t see.
“This didn’t, it nowhere near showed that, and the longer it took, the more worried I got.
“I’m so, so surprised from coming away on Thursday from that meeting to have that decision today.”
Last weekend in Chelsea’s 4-2 win over Burnley, Lampard’s side were awarded a penalty on the field only for the decision to be overturned by VAR, with Callum Hudson-Odoi instead booked for diving.
“I reference back one week to Hudson-Odoi – he goes down, has a hand on the back, gets a yellow card and that’s overturned the other way around,” Lampard said
“We’re not in a great place with it, are we?
“Anything that takes that long means there’s something they’re not sure about, so why aren’t we using the screen at the side of the pitch?”
Lampard added: “We’re in a really dangerous place and you’re going to be tossing a coin every week to see what decision you’re going to get.”