Champions League matches on despite ash
UEFA told Reuters on Sunday that their travel department and other officials had been in close contact with all four clubs and that there was no problems with the travelling teams reaching their destinations.
Inter Milan are at home to European champions Barcelona on Tuesday with Bayern Munich at home against Lyon on Wednesday.
"Barcelona are travelling to Milan by bus and Lyon are also planning to go to Germany by road as well," said UEFA's director of communications Rob Faulkner.
He added the situation regarding Thursday's Europa League semis between Atletico Madrid and Liverpool in Spain and SV Hamburg and Fulham in Germany would be reviewed on Monday.
"We have been in touch with those clubs as well and the situation is being closely monitored.
"The Champions League games will definitely go ahead as planned. The only issue is that some match delegates might have to be changed, but a decision can be made on that later. Tuesday's referreeing team is not being changed but a back-up team have been alerted in case."
Barcelona left by bus for Milan on Sunday, the European Cup holders said.
The La Liga leaders will travel in two buses the 634 kilometres to Cannes on Sunday and stay overnight before covering the last 351 kilometres to Milan on Monday, the club said on their website.
Both Barcelona and Milan airports were closed on Sunday.
After Saturday's 0-0 draw at city rivals Espanyol, Guardiola had played down the significance of a possible road trip to northern Italy.
"It wouldn't be the best but there are teams from the lower leagues that travel 17 hours by bus," he told reporters.
"A semi-final is enough to help anyone get over any tiredness."