Liverpool are set to complete the first of three possible summer raids on Saints with the capture of star striker Rickie Lambert in the next few days.

The Reds expect to put the 32-year-old through a medical today, before handing him a two-year contract, having agreed a fee worth up to £5m, plus add-ons.

This season’s runners-up in the Premier League will then look to seal moves for Adam Lallana, having lodged an improved £25m bid last night, and Dejan Lovren later in the summer.

On top of that, Saints are also attempting to resist a last-ditch attempt from Manchester United to push through a deal for Luke Shaw before the World Cup begins.

United, who have offered £27m for the 18-year-old left-back, are understood to have been in touch yesterday in a bid to complete the transfer before the player flies off to Miami tomorrow for England’s pre-Brazil training camp.

Once that point has passed, it will be complicated for any deals to be concluded until the squad returns from South America.

Saints, for their part, ideally want to put the matter on the backburner until after the tournament, when a new manager will be in place at St Mary’s, and supporters will expect them to do just that.

Chairman Ralph Krueger had said this week that all transfer dealings were on hold until a replacement for Mauricio Pochettino, who walked out on Tuesday to join Tottenham, was found.

In hindsight, that has turned out to be a somewhat embarrassing statement, given the decision to agree a fee for Lambert, but Saints felt under far more pressure to deal with that situation quickly than they do with any of the others.

Liverpool’s approach came out of the blue on Thursday, after Krueger had spoken, with the Reds issuing an ultimatum that the deal had to be in place by the end of the weekend, as they would not wait until after the World Cup and would instead turn their attention elsewhere.

Knowing that Lambert’s heart is set on a dream move to his hometown club, Saints felt that holding onto him against his will could do more harm than good, and so reluctantly accepted, although soothing fans’ feelings that they have been bullied into the transfer will not be easy.

They have intended to be firmer when it comes to Shaw and their captain, Lallana, who had been the subject of a initial £20m bid from Liverpool, while the Reds are also understood to be plotting a £15m move for centre-half Lovren.

As would be the case with Lovren, if they do lose Lallana, Saints will want to receive a major sum, especially with Bournemouth owed 25 per cent of any fee for their skipper.

Having all-but-sealed Lambert's move, Liverpool appear to now be applying similar pressure on Saints to conclude a deal for Lallana.

Lambert’s move to Anfield, from where he was released as a schoolboy, is expected to be confirmed tomorrow at the earliest, or more likely early next week.

His former club, Bristol Rovers, are said to have a 20 per cent sell on fee, meaning they would receive about £1m.