Birmingham, April 18 -- Ollie Watkins scored again as Aston Villa knocked Bologna out of the Europa League in a 4-0 rout to set up an all-English semi-final against Nottingham Forest. Unai Emery's team reached its second European semi-final in three seasons with a 7-1 aggregate victory. Watkins opened the scoring at Villa Park with what was his 100th goal for the club. Villa reached the Champions League quarter-finals last season and is on course to secure a spot in the lucrative top-tier competition next campaign while sitting fourth in the Premier League. Forest made the semi-finals by beating 10-man Porto 1-0 in what's been a successful return to European competition after a 30-year absence. It advanced 2-1 on aggregate after last week's draw in Portugal....