Jackson ran 13.14sec in the 110 metres hurdles - a time bettered this year only by Larry Wade, who a week earlier ran 0.02sec quicker. But the conditions in Stuttgart were cooler than the sunshine the American had enjoyed in Eugene.
The Welshman was challenged all the way by the Cuban Anier Garcia, last year's World Cup bronze medallist who ran 13.17sec. Falk Balzer, who Jackson beat for the European gold in Budapest last August, was third in 13.30sec.
Jackson said: "I have to be happy with my performance. It is definitely one of the best and fastest starts I have ever made to a season. Yes, I was really quick out of my blocks and that's what you get after gaining speed after an indoor season.
"Stuttgart has always been one of my favourite venues and that's why I did the lap of honour. I showed out there I am already in shape to race against anyone now. The race was what I needed. The conditions weren't perfect but the opposition was good."