Hospitals will be under "additional pressure" as thousands of junior doctors go on strike and patients should seek help elsewhere, NHS bosses have said.
Around 100 picket lines are being put in place for Tuesday's strike, with a large concentration in and around London.
NHS England said 1,425 inpatient operations and procedures were being cancelled as a result of the strike alongside 2,535 outpatient ones.
It said there are around 4,000 cancellations in total, of which 3,400 are on Tuesday.
Some 654 cancellations - 192 inpatients and 462 day cases - are in London.
Labour leader Jeremy Corbyn said it was vital that an agreement was reached "quickly" on the dispute, which could lead to four days of industrial action.
Boris Johnson has said the British Medical Association (BMA) leadership "is in the grip of advanced Corbynitis. They need to get back round the table".
In advice to patients, NHS England said: "Urgent and emergency care services will be available as normal but hospitals are expected to be under additional pressure.
"Where possible, people should contact their GP, seek advice from their local pharmacist, call NHS 111 or consult the NHS Choices website.
"Where it is an emergency, people should call 999 or go directly to A&E.
"GP services will be available as normal and we would encourage anyone who thinks they will need an appointment to organise this before industrial action begins.
"People should be particularly attentive to their health over this period and look out for more vulnerable members of their families and communities."
Talks aimed at resolving the dispute over a new contract failed on Friday, although further talks will continue.
Junior doctors are set to provide emergency care only for 24 hours from 8am on Tuesday.
This will be followed by a 48-hour stoppage and the provision of emergency care only from 8am on January 26.
On February 10, there will be a full withdrawal of labour from 8am to 5pm.
Mr Corbyn told BBC Radio 4's Today programme: "We should recognise that junior doctors are qualified, extremely hard-working, deserve to be treated properly and (Health Secretary) Jeremy Hunt should now come to an agreement with them."
He added: "I hope that Jeremy Hunt realises the need to come to an agreement very quickly."
The basis for the current round of negotiations is the Government's offer from early November, including an 11% rise in basic pay for junior doctors.
This is offset by plans to cut the number of hours on a weekend for which junior doctors can claim extra pay for unsocial hours.
Currently, 7pm to 7am Monday to Friday and the whole of Saturday and Sunday attract a premium rate of pay.
Under the Government's offer, junior doctors would receive time-and-a-half for any hours worked Monday to Sunday between 10pm and 7am, and time-and-a-third for any hours worked between 7pm and 10pm on Saturdays and 7am and 10pm on Sundays.
Junior doctors would also receive on-call availability allowances, ranging from 2% to 6% of basic pay, as well as payment for work undertaken as a result of being on-call.
The BMA has said there are still several areas of dispute, despite Mr Hunt saying the only sticking point is weekend pay.
Rob Webster, chief executive of the NHS Confederation, told the Today programme that plans to cope with the strike meant potential harm to patients had been "minimised" but "both sides have to get back in the room with Acas".
England's chief medical officer Dame Sally Davies said on Sunday the strike would "lead to patients suffering".