Susan, apologies, will rephrase in future
Good choice Ikle, tired body and tired mind don't really work, see below!
I managed to get on the wrong underground train tonight,.. Heading for Chester which is 10 miles in wrong direction.. Happily reading paper and 15 minutes in before I realised. Very Doh moment.
Legs and knees a bit tired after the weekend 22+14 so good in reality, backed off original plan to do 4 miles to club, and tempo there to a Steady 5 miles at 8mm. No heroics. No medals for your midweek run as a pal says and very good common sense.
Scott, I'd be wary of doing 20 mile at race pace so early for both you and your friend. It serves no purpose to race your training. It will take something out of your legs for a few weeks and possibly affect speed sessions and tempo runs for your half training.
My coach last year (sadly passed away now) advised marathon pace +60 secs or more,... even on a 20 mile "race" only 2 x 5-6 miles at MP, and that was 4-5 weeks before my marathon. Save race pace and faster for tempo runs.
Are you ready to do a 20 mile run anyway so soon? If you've been keeping things going to 13-15 miles then 20 will still be a hard jump. maybe get him to do 5-7 miles first then join him for the rest so both of you happy?