I'd assumed that the lack of a clock was a uefa thing - along with the change of stadium name and fancy dress for the ball boys - but regulation 33 on clocks states otherwise so it must have been a club thing, but I can't think why as the regulation seems identical to Premier League games!!
"33.01 Clocks in the stadium showing the amount of time played may run during the match, provided they are stopped at the end of normal time in each half, i.e. after 45 and 90 minutes respectively. This stipulation also applies in the event of extra time (i.e. after 105 and 120 minutes)."