"Watching from the sidelines will be very frustrating and difficult," he said. "It has not been nice watching them practise, never mind play a Test match. When I did something similar against New Zealand a couple of years ago I did not stay at the ground, I went off to see a knee specialist in Sheffield. So this will be the first time I have sat in the dressing room and watched a Test as captain.
"It is frustrating for me and the team because we got a bit of momentum up during the Ashes. But the players are all behind Marcus and they are looking forward to a big challenge. The side may have lost their captain, but the vibe around the team is very, very good."
Vaughan's presence in and around the dressing-room will make it harder for Trescothick to be his own man, but he has promised to stay in the background. "Ideally you don't want to get too close once the game starts. I will have some input at the team meeting, but once the game starts it is over to Marcus, Duncan [Fletcher] and the 11 players to come up with the right tactics for this pitch, against this opposition.
"I told Marcus to captain the side the way he wants to do it. For me to stand there and try and take part once the game has started is totally wrong. But I won't disappear. Marcus is fine with me being around."
However, Pakistan coach Bob Woolmer last night questioned Trescothick's ability to lead the side. "Michael is a very good captain and he has turned England into a very fine side. Whether the vice-captain can take over that role and be as good - there is always a question mark."
That Vaughan is still in Pakistan is, in many ways, a positive sign. When he fell to the floor at the Bagh-I-Jinnah ground in Lahore, many, including Vaughan himself, feared the worst.
"When I first did it I thought I would be on the next flight home," he said. "I am now just trying to make gradual progress. There was never any real chance of me playing in this Test match, but there is a slight chance I could be fit for the second, so I will be doing all I can over the next few days to try and get it right. If I don't I will obviously have to disappear, but I will give it my best shot.
"It is slightly different to the last time, when I did it against New Zealand, and it has felt a little bit worse. At Lord's I did it twisting in the nets, and if you do it doing something a little bit unorthodox you can sometimes understand it. But when it goes when you are running in a straight line it is a bit more of a worry.
"Since Lord's it has been fine, but there can be no doubt I do have a slight problem with the knee and it needs to be sorted out sooner rather than later. I do not feel I am nearing the end of my career just yet."
Time here is not on Vaughan's side. When he injured the knee prior to the first Test against New Zealand in 2004, he had 17 days to recover before England were due to play again. Here, having sustained a worse injury, he has only 13. In the 18 months that have passed, the condition of his knee is unlikely to have improved so the England players may have to become accustomed to the sound of Trescothick's voice.
Vaughan's absence leaves England with an inexperienced middle order, but he is confident that Ian Bell, Kevin Pietersen and Paul Collingwood will rise to the challenge. "It is youthful, but it has a lot of talent. Over the last year they have all been able to learn and adapt very fast. This will be a tough challenge for them because not many of them have played in these conditions before, but the way they have learnt in the past should hold them in good stead.
"I have looked back at a lot of the stats from the last series here. In the first Test, in Lahore, we batted for more than 200 overs to score 480. During the summer we were scoring at more than four runs an over, but that probably won't happen here, so we may have to show patience with both the bat and the ball."
They will also have to cope with Danish Kaneria's leg-spin, much as they did that of Shane Warne's during the Ashes. "Danish is the key man for us," Inzamam-ul-Haq, Pakistan's captain, said. "In the last two or three years, he has bowled very well - and we will be looking to him again.
"We have a little bit of an advantage because Vaughan is not playing," he added. "But we know the England team are still very strong."Reuse content