Cassio Gabriel, Bipin Singh, Igor Angulo and substitute Ygor Catatau were on the scoresheet for the ISL leaders.
FC Goa were off to a flyer as Guarrotxena scored after just two minutes. Brandon Fernandes played a short corner to Edu Bedia on the right flank. The Spaniard whipped a cross in as the ball missed a cheeky flick from Redeem Tlang before finding Guarrotxena, whose decisive tap-in put the Gaurs ahead.
All the results from the I-League and ISL matches played on Saturday
Southampton confirmed that they had signed 23-year-old Walker-Peters, who spent the second half of last season on loan at the club. British media put the fee at 12 million pounds.
Chennaiyin's defense was a tough nut to crack as Eli Sabia and Vishal Kaith came with crucial interceptions and blocks to deny Sunil Chhetri and Paartalu.
FC Goa handed defending champions Chennaiyin FC a 3-1 defeat in an Indian Super League (ISL) match at the Jawaharlal Nehru Stadium, in Chennai, on Saturday.
Defending champions Bengaluru FC registered their first victory in this season's Hero Indian Super League, thrashing Chennaiyin FC 3-0, in Bengaluru, on Sunday.
ATK may have qualified for the play-offs, but the loss came as a big blow to their AFC Champions League qualifying aspirations with FC Goa taking a three-point lead at the top with only a match left for the league stage to conclude.
NorthEast United scored in the final minute of the added time to hold defending champions Chennaiyin FC to a 3-3 draw in a thrilling match and kept themselves alive for a play-offs berth in the Indian Super League football in Chennai on Saturday.
In what was a repeat of last season's final at the same venue, Miku's 41st minute strike was enough for the Blues to overcome the visitors' challenge.
FC Pune City's home woes in the Hero Indian Super League continued as they dropped precious points in a 1-1 draw against Chennaiyin FC at Shree Shiv Chhatrapati Sports Complex Stadium, Balewadi, Pune, on Sunday.
Defending champions Chennaiyin FC rallied from one-goal deficit to play out a 1-1 draw against Atletico de Kolkata in their Indian Super League football match in Chennai.
News of all that's transpired on and off the football field
The draw, Goa's sixth on the trot, helped the Gaurs climb to the third spot on the table.