Complex sentence: Led by Maradona, Napoli won their only Serie A Italian Championships in 1986/87 and 1989/1990, placing second in the league twice, in 1987/88 and 1988/89.
Split into simpler sentences: Led by Maradona, Napoli won their first ever Serie A Italian Championships in 1986/87. ' Napoli would win their second league title in 1989/1990, and finish runners up in the league twice, in 1987/88 and 1988/89.