Belmont Stakes action picked up Sunday morning with solid works by Kentucky Derby winner Monarchos, Derby runner-up Invisible Ink, and Arkansas Derby and Spiral winner Balto Star, all of whom worked five furlongs over a muddy track.Monarchos, who apparently loves a wet Belmont surface, once again skipped over it, working in a sharp 1:00 2/5. After fractions of :24 1/5 and :36 3/5, the son of Maria's Mon flew home in :23 4/5 before galloping out a strong six furlongs in 1:13.Invisible Ink, who has not run since the Derby, got his five furlongs in 1:02 1/5 after an opening quarter in :24 3/5. The son of Thunder Gulch galloped out his six furlongs in 1:15 3/5.Balto Star, the likely pacesetter in the Belmont, went off his opening quarter in a slow :25 1/5, then closed well to complete his five furlongs 1:01 2/5 before galloping out in 1:14.The works will continue over the next couple of days, with A P Valentine scheduled to work at Belmont tomorrow, while Point Given and Dollar Bill will work at Churchill Downs tomorrow or Tuesday before shipping to Belmont on Wednesday.The form of Team Valor's English invader Dr Greenfield received a major boost Sunday when Grandera, who was second to the son of Dr Devious in the Dee Stakes last time out, finished a troubled third, beaten a head and a half-length, in the French Derby at Chantilly. The son of Grand Lodge was shut off trying to squeeze through on the inside two furlongs out, then was shut off again one and a half furlongs out. He'll likely go next in the Irish Derby.