German invader Senex, a winner of just one previous race in 13 tries, surprised his rivals with a convincing 2 1/2-length victory in the $534,204 Gran Premio di Milano (Ity-I) at Milan's San Siro racecourse. Senex, sent off at 17-1, had several placings in group competition for trainer Hans Blume, who credited the good turf for the 4-year-old colt's improvement. He said the Canadian International (Can-I) at Woodbine Oct. 24 is in the long-range plan for the German-bred son of Pelder.Jockey William Mongil held Senex toward the back of the pack of the seven-horse field in the 1 1/2-mile test as Maktub set an even pace. Senex advanced on the leaders a quarter-mile from home and took the lead at the furlong mark, winning while ridden out. The time was 2:28.7Maktub held on for second, a length ahead of the The Great Gatsby. Italian hero Altieri was fourth and returned lame for trainer Vittorio Caruso, who said the colt took a bad step and bumped the rail entering the straight.Italian Derby (Ity-I) winner Groom Tesse finished last and was never a factor.