Martinez admitted at times his players played with apprehension but was overall delighted with the way they came out on top as he goes after a second successive FA Cup after guiding Wigan Athletic to the title last season.
"We are very satisfied because all you are looking for is a win to get into the next round," the Spaniard said.
"We were a little bit anxious and feeling the role of playing at home and expecting to get into the next round and we were too cagey with our possession allowing Swansea to get well organised.
"The second half was very different, we controlled the game, creating good opportunities and limiting Swansea to very little."
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