In a large skillet heat oil over medium-high heat 1 to 2 minutes. Add shrimp and garlic; cook and stir 2 to 3 minutes or until shrimp turn pink. Transfer to a platter; set aside and keep warm.
Add tomatoes, lemon juice, oregano and red pepper flakes to skillet; stir. Bring to boiling; reduce heat and cook 10 to 12 minutes or until juices reduce slightly. Season with salt and pepper to taste.
Meanwhile, cook the spaghetti al dente according to package directions. Drain; transfer to a large, shallow serving bowl.
Return shrimp to skillet; stir to coat. Spoon shrimp and sauce over pasta. Serve immediately.