Heat oven to 375°F. In medium bowl, mix pasta sauce, water and garlic powder. In ungreased 13x9-inch (3-quart) glass baking dish, spread about one-third (1 cup) of the pasta sauce mixture.
In medium bowl, sprinkle chicken tenders with Italian seasoning. Stuff chicken into uncooked manicotti shells. Place shells on pasta sauce in baking dish. Pour remaining pasta sauce mixture evenly over shells, covering completely.
Cover with foil. Bake 45 to 50 minutes or until shells are tender. Sprinkle with cheese. Bake uncovered 2 to 4 minutes longer or until cheese is melted. Sprinkle with tomato. Serve with pesto.