adding zeroes to all single digits

Shell Programming and Scripting
1

I have got a file that contains both single and double digits like this
10 3 48 39 20 6 8
and i want to add zeros in front of every single digit to become double digits like this
10 03 48 39 20 06 08

I tried using Sed
sed 's/\([0-9]\)/0&/g' filename
or
sed 's/\([0-9]\)*/0&/g' filename
but i ended up have zeros added to every thing in the file can someone pls help me
thank you for you help

2 
awk '{ for (i=1; i<=NF; i++) $i=sprintf("%02d", $i); print; }' filename
3

thank you
your help was great

4

another way, if you still want to work with sed:

cat filename | tr ' ' '\n' | sed -e 's/^\([0-9]\)$/0\1/' | tr '\n' ' '